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Big Truck I work on Hino trucks. I'll answer any questions I know the answers to.

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floridawheels

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(PART 1)

A/C Heater blower motor and A/C in general


First let me say THANK YOU Mr. Greasy for all the help you have given me!!


Now, about that blower motor and A/C....


2007 Hino 338 - I live/work in Florida and I do not like to be hot. I have had this truck going on 2 years now. First summer was rough, second summer, much better. I'll condense the story greatly.


I have a large sleeper (96") on my truck and of course it has an underbunk A/C unit tied into the factory dash system.


The air blowing from either the dash or the bunk unit was cool but I could never get it to be real cold. At one point the fan started blowing less and less. What follows below will bypass all the trials, tribulations and experiments to try to fix those issues and i'll get right to the bottom line of what was done to finally effectively fix everything.


The fan motor was replaced, air flow improved for about 2 months, then quit again. The cause was a melted switch AND plug. The fix was to replace both the switch and the plug. The part numbers for the plug are hard to find but it is available. I got it as a plug and had to order a pigtail wire for each of the contacts, (It comes with the contact and about 4" of wire). There are different colors and sizes. With enough searching your parts person can eventually find the correct part numbers.


Pull the dash trim off and remove the 3 screws holding the A/C control panel. You won't be able to pull the control panel out very far because of the control cables for the temperature valve and air doors but you can get it out enough. Pull the plug out of the back of the switch, if it looks melty, replace both the switch and plug. (You can of course replace just the switch but most likely you'll soon be replacing the switch again and this time the plug as well - Ask me how I know this... Sigh)


When you go to replace the plug do it correctly or your going to have problems later. When splicing wires I only ever either solder and marine grade heat shrink or use high quality (expensive) marine grade crimp terminals with heat shrink. (The marine grade heat shrink has glue inside it to give you a weatherproof connection). Either of these methods give you a high quality connection that will last over time and will not cause a heat issue. The marine grade heat shrink helps act as a strain relief for the connection by physically bonding to the wire preventing it from wanting to pull out of the connection. Use caution when heating the shrink tubing not to melt other things in the area. Cover them with something... Aluminum foil works well as a "Blast shield" over the things behind your connection. Also, Harbor Freight sells a decent heat gun for about $20 and they have an accessory kit for it that has a few different "tips" or nozzles. 1 of them has a "U" shaped end that partially captures the hot air and directs it to the back of your connection making it much easier to properly apply heat to all sides of your connection. That nozzle kit is about $10.


So now you have a new switch and plug but your still not getting the proper air flow... Of course I should mention the AIR FILTER... It is located under the dash right where your passenger left foot is. I clean mine WEEKLY, more often in the summer because it gets dirty faster in the summer. All you have to do it grab the tab and pull it out. It sort of "hinges" in the back so the front comes out first (Front as in front of the truck). Take it outside, pay attention to the wind and just tap it on something hard, like the bumper, step, whatever. All the crap will fall off. It looks cheap and flimsy to me so I bought another one (About $20 if I remember correctly) to have just in case, (I am a firm believer in having spare parts available (When possible/practical) when you need them, not having to wait weeks for Hino to get around to shipping/delivering them). So far I have not had to use it.


The fan - Replacing the fan can look like it will be a real pain in the butt. It sort of is but it is also not that bad. The first time I installed a new fan, (yes, the first new fan...) I did just the fan. Pull off the panel over the fuses and the lower center dash panel just to the left of that. There are a couple screws in the center panel, make sure you remove them before you just try to snatch it out. I found the simplest way to remove the fan is to remove the top half of the fan housing assembly bring it and the attached fan out of the dash. Swap out the fan and reinstall everything in reverse order.


That said.... There is also a RESISTOR in the electric system for the fan. This resistor wears out and can/will cause you issues. I did not replace the resistor the first time. This last time I did, more on that later. The resistor is located pretty much on the firewall behind and to the left of the blower housing. Once you have the center trim off, assuming you know what your looking for, you can see the resistor. Seeing it is one thing, touching it.... well that's another story... LOL.. However, once you have the upper fan housing out, getting to the resistor is not all that hard. So, If... IF your going to replace the resistor, when you have the housing apart to replace the fan is an ideal time to do it.


So, this second time I replace the fan, (I use my A/C 6 days a week, pretty much 24 hours a day. The fan lasted about 1 year, roughly 7,500 hours of use - You would think it would last longer than that?!?) Anyway, The second fan replacement I also purchased the resistor (About $45). Once I removed the fan I plugged the new fan in and tested it. It did work, indicating that the resistor was still serviceable. I had the new resistor on hand in no small part because Mr. Greasy had told me to try the resistor first, (And the local parts people also told me that the resistor often goes out). Since I had a replacement resistor on hand and now had access to the old resistor I figured I might as well install the new one even though the old one seemed to be working. Everything was reassembled.


NOTE: Before replacing the fan for the second time I inspected the switch/plug. This time both looked to be in perfect condition but this of course might not always be the case so it is a real good idea to pull the dash apart enough to inspect those parts before just going straight to fan replacement.


With both the motor and resistor replaced the air flow from the dash vents is AT LEAST 25% more now than it has ever been since I bought the truck. Next year when the fan goes out again, I'll be spending the extra $45 for another new resistor as well.


Now about the temperature of the air coming from the vents. I'll not go into the entire theory of how the A/C system goes about making the air cold but I will tell you it is a pretty particular system and things have to be functioning just right to get optimum results (The coldest air possible).


I went to a local A/C shop and they said they thought that even though the pressures seemed to be in the acceptable range that probably my compressor was weak. Also, with the system that was as old as mine (remember, truck is a 2007) the condenser (The radiator looking thing on the front of the truck) might be an issue.


I spoke to Mr. Greasy about all of this and he recommended that I check the air flow through the condenser/radiator because the air passages often get clogged with bugs and other debris greatly reducing the ability of the air to pass through. Mr. Greasy also strongly advised against using a pressure washer on the condenser as it is not real strong and the pressure can easily damage it. After having removed mine and looked at it, I will strongly second that. In my particular case there was absolutely minimal crap blocking the air so what was there was removed and onto the next step.


Fan clutch - At highway speed the air was cool, almost cold. At idle is was barely cooler than outside air. This of course tells us that the air flow at idle is not sufficient. I could use the high idle know bit increase engine RPM which helped some. Opening the hood also helped if I was going to be somewhere for an extended period of time. But this was not really an acceptable solution. I felt strongly that the fan clutch was not functioning properly so I discussed this with Mr. Greasy. (And later Hino techs at 2 different dealerships that looked at it). There really is not a definitive way to easily tell if the clutch is working or not but I finally decided my sanity and comfort was worth the almost $500 for a new fan clutch so I bought and installed a new one. It did not seem to make any difference at all. Not only did the air not get any colder but it did not seem to make any difference in engine temp and knowing what it is supposed to sound like, I did not hear any difference either.


Roughly 6 months after installing the new fan clutch my turbo went out. I took it to a dealership (Not either of the 2 that had looked at my fan before). While the mechanic was changing out the turbo I mentioned the fan clutch. He gave it a spin and immediately said,"This clutch is no good". I had them install a new one and send the "Other new one" in for warranty claim, (That's another story buy I did eventually get a warranty refund on that). So it seems that the new one I had first installed was likely no good right from the start. With the second new one on the truck the temps did come down some and it does seem to sound more like expected.


Air still not really cold enough - OK, now we are going all in for cold air. New A/C compressor, new condenser, new dryer, new expansion valve. Careful and 100% complete flush of entire A/C system. (Note, the dryer on this system is inside the condenser. It is individually replaceable but when you get a new condenser it comes with a new dryer installed). More improvement but still not where I wanted to be.


More discussion with the A/C shop guy and a visit to 2 different Thermo King shops. The conclusion was that perhaps the stock compressor and or stock condenser was not fully up to the task of providing the needed pressure and system cooling to provide the needed "Stuff" for both the dash and underbunk systems. After much research and discussion it was determined that there was not a feasible replacement for the compressor but enhancements could be made to the condenser part of the system.


Now to help you understand some about this I'll give a simple and partial explanation of how part of the A/C system works. When the compressor does it's job of compressing the Freon gas the gas gets hot. This hot gas needs to be cooled down in order to do it's job of making the air cold. The condenser is the part that does the cooling of the hot Freon gas. It was reasoned by those I discussed this with that perhaps there was simply not enough condenser area for the gas to properly cool. Installing a larger condenser in the factory location was not practical.
 
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floridawheels

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(PART 2)

We had basically 2 options, install new plumbing and bypass the factory condenser completely and replace it with one mounted somewhere else that was much, much larger, (A company called Red Dot that specializes in HVAC for commercial trucks, heavy equipment and military vehicles has several units i/we considered) or, leave the factory condenser and plumb in a second small condenser to compensate for the addition of the underbunk unit.


After considering the cost of the plumbing, installation and the fact that the factory condenser was now brand new (A shame to waste it) we decided to add a second condenser and fan. This was installed under the sleeper. Anytime you have the A/C system open to the outside air it is recommended that you replace the dryer at the same time. Since the dryer was basically brand new, and expensive to replace, and would have required a drive of 150 miles round trip to get we simply installed a new stand alone dryer, designed for a system about 50% larger than what we were working with. The new dryer is installed back by the new condenser and that component cost about $50.


Now we have COLD air. This was installed back about the middle of last summer. With outside air temperature of basically 100 degrees (F) my dash and bunk units were pumping out 47.6 degree (F) air!! Finally...!! Even at idle now with the second remotely mounded condenser/fan well away from engine heat it was still blowing in the low 50's (F).


NOTE: I did discover that the is a company that was making the necessary brackets to install a second A/C compressor on my truck. They no longer keep that kit in stock but the individual parts are still available and they said they could assemble a kit for me in a day or two. Just the bracket kit was about $800. I had considered adding a completely separate A/C system using Red Dot parts to put a huge condenser on the cab roof that would then feed inside cab roof mounted evaporator/blower/control unit and an additional underbunk evaporator/blower and separate control unit. The advantage of having done that would be a completely separate system that would easily cool the cab, sleeper and then some. If either system went out I would still have the other working as a back up. Had the addition of the second remote condenser not worked like it did this was just about the only next/other option. To go with the second option would have run about $3-4,000 by the time it was all done and operational.


Actually there was one other option and that would be buy an APU and run it pretty much 24/7 shutting the truck off during sleeping but leaving the APU running all the time to supplement the truck A/C. While I certainly understand the other "Normal" benefits of an APU (And actually do want one) the $10-15,000 purchase price of one and then having to run it 24/7 seemed like not a rational way to go as a solution to not having cold enough air while driving.


So, there you have it. My almost 2 year adventure of trying to get cold air condensed into one simple (?) post.... LOL... I hope it was not to long of a read, I hope it was understandable and I hope it helps.


Just for the record, this post is a partial attempt on my part to "Give back". Mr. Greasy has helped me more than any of you will ever know. The main thing he helped me with was mechanical issues with the fuel system and transmission. Later, when I have more time I'll write up a report about that in the hopes that it will save others from the same problems I had and also that it will save Mr. Greasy from having to answer the same questions again and again.


Drive safe...

EDITED TO ADD: At one point, before the additional condenser install but after the replacement of the A/C compressor, factory condenser and so forth, (And during the heat of summer) I noticed a great deal of heat radiating from under the dash into the cabin.

After some conversation with Mr. Greasy the decision was made to terminate the water flow from the engine to the heater core to see if this relieved the heat issue which would hopefully then help with the cooling of the cabin.

The easy and inexpensive way to do this would be to simply remove the outlet and return hose at the engine and install a replacement hose that just goes from one to the other. This would allow the water flow to continue and eliminate any potential issues caused by simply capping off the outlet and inlet. Simple but also a real pain when the occasional need for cabin heat arises.

To do this the "Right way" I obtained 3 brass ball valves and an assortment of hose barbs, short double male brass fittings, 3 brass "T" fittings and hose barbs. Keeping in mind that I have an underbunk HVAC component as mentioned above in relation to the A/C side, it also has a heat side so there are "T" fittings in the current hoses and a shut off valve specifically for that unit on the unit itself.

I cut the factory hoses between the factory component and the aftermarket (underbunk water supply) "T". At this point I installed the "T" and then the ball valve. This was done on both the outlet and return sides. The 2 "T"s were connected with a ball valve between them as well.

All of this mess is above the valve cover well out of the way of any moving or hot parts.

To operate:
Summer mode; (Bypass the heater core) turn both supply and return valves off, open the bypass valve.
Winter mode; (Allow water to the heater core) Open both supply and return valves, close bypass valve.

I used all manually operated ball valves. There are 12 volt electric valves available and wiring them for the needed sequence would be super easy. (But the electric valves are rather expensive). This would allow on the fly putting heat back into the cabin without having to stop, get out, open the hood, change 3 valves, close hood, get back in truck. This would be handy this time of year (Mid February - in Florida) when it is A/C during the day but heat needed at night. However, even though A/C is needed during the day, it is not so hot outside that with the valves being open it is not really a problem as the A/C is good enough to still make it nice and cool in the cabin. When the outside temperature is in the high 90's or even 100's, well, that is when the valves really make a huge difference.

So, did the modification produce the desired result? Absolutely yes. The dash heat stopped immediately and the temperature of the cold air from the A/C ducts decreased (Got colder). I did not take actual measurements but the results were enough that it was easily noticeable.

Bottom line on this modification is that anyone operating in the southern part of the country on a regular basis during the summer who is not getting cold enough air from the dash and has already had the system checked for other issues AND notices that the under-dash area seems especially hot then I can highly recommend this modification.
 
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greasytshirt

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Picture time!

If you're gonna hit something, try and hit it with a part of the truck that's cheap. It would have been cheaper to rip the rear axle out of a truck than to hit the aftertreatment system.

1487030800535.jpg

Sent from my XT1585 using EO Forums mobile app
 

greasytshirt

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Gee, I didn't know there was any part of a Hino that is cheap (as in inexpensive)...! LOL.
We're looking at least $10k reduced to dumpster ballast right here. Whoever was driving also managed to put diesel in the DEF tank.

The frame is also bent all to hell, but that part is easy.
 

Ragman

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Gee, I didn't know there was any part of a Hino that is cheap (as in inexpensive)...! LOL.
We're looking at least $10k reduced to dumpster ballast right here. Whoever was driving also managed to put diesel in the DEF tank.

The frame is also bent all to hell, but that part is easy.
Might have been a sprinter driver.
 

Hino123

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Gee, I didn't know there was any part of a Hino that is cheap (as in inexpensive)...! LOL.
We're looking at least $10k reduced to dumpster ballast right here. Whoever was driving also managed to put diesel in the DEF tank.

The frame is also bent all to hell, but that part is easy.[/QUOTE

Ha, nice one! Had a customer towed in with a P20EE for low SCR efficency last month. After looking up in the t-pipe we noticed a hole in the scr. The tail section was removed and revealed multiple holes were drilled through the SCR. Long story short, the customer thought the SCR was the DPF, and they drilled it out for better exhaust flow :) It ended up costing them almost 6k!
 

greasytshirt

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Ha, nice one! Had a customer towed in with a P20EE for low SCR efficency last month. After looking up in the t-pipe we noticed a hole in the scr. The tail section was removed and revealed multiple holes were drilled through the SCR. Long story short, the customer thought the SCR was the DPF, and they drilled it out for better exhaust flow :) It ended up costing them almost 6k!
I'd loved to have been a fly on the wall for that conversation. On a related note, I would make the worst service manager ever. I've got a big hole in my brain-to-mouth filter.
 

greasytshirt

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For example:

Phone rings. Frantic customer on other end. I'm immediately regretting answering the phone. "Hey man, I've got air leaking really bad out of a brake chamber. Is there ANY POSSIBLE way to fix this so I can get home?"

Sure. Put in the cage bolt, tighten it all the way up, then clamp off the air lines. Got any tools?

"No"

Well, that's a problem. Any auto parts stores nearby?

"Yes, there's an Autozone across the street. Hey, If I do this, can I keep driving it?"

Hell no, this is totally illegal. If DOT catches you, they're setting you on fire.

"I can't do that!"

YOU ASKED FOR ANY POSSIBLE SOLUTION.

I don't answer the phone any more.
 
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greasytshirt

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It looks like Hino trucks have their own dedicated forum here in EO. This thread isn't getting removed, but instead no one will be able to reply to it. This will make searching for answers easier, without having to read a 92 page thread.
 
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