AC question

[layoutshooter]

Any AC gurus out there? We are having a rather annoying problem.

The AC keeps cutting out. It will run fine for a few hours then cut out. Sometimes, if it is working and I shut down the truck it can take a few hours to get the air working next time I start it. It also tends to shut down when running below 55.

One shop "fixed" it, said it was low on coolant. It worked for a day or two, did the same thing.

Another shop said that the expansion valve was freezing up and needed replaced, they did not have one.

Took it to another shop. They said it needed harness and a drain line, there was a service bulletin on it. They did that job. Same thing a few days later.

Any ideas? Could it be that expansion valve? It works good when it works. Cold and drops the humidity find.

 

[blackpup]

Did any of the shops clean the filter or the evaporator coil ? When the unit freezes up dose the fan quit blowing gradually or all at once ?

jimmy

 

[paullud]

Possibly the clutch on the pump.

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[layoutshooter]

Cleaned it all, replaced the "dryer"? It cuts out quick, you can hear it cut out and then back in if it does. The entire system has been vacumed out and recharged twice.

 

[paullud]

You can say that again.

Aww you took it down no my post doesn't make sense.

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[blackpup]

Cleaned it all, replaced the "dryer"? It cuts out quick, you can hear it cut out and then back in if it does. The entire system has been vacumed out and recharged twice.

We may be on two different pages here. Sometimes the evaporator coil that is inside cab will get so dirty that coil will start freezing over and stop cooling and that will also act like an expansion valve not metering correctly . Something like an radiator being so dirty that it cannot work properly.

When you said freezing up, dirty coil is the first thing that came to mind.

jimmy

 

[layoutshooter]

We may be on two different pages here. Sometimes the evaporator coil that is inside cab will get so dirty that coil will start freezing over and stop cooling and that will also act like an expansion valve not metering correctly . Something like an radiator being so dirty that it cannot work properly.

When you said freezing up, dirty coil is the first thing that came to mind.

jimmy

The one shop said there was ice on the expansion valve. Another said no. The temp on the engine is fine.

 

[paullud]

The one shop said there was ice on the expansion valve. Another said no. The temp on the engine is fine.

He is talking about a part of the AC unit that is like your heater core.

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[Ragman]

Any AC gurus out there? We are having a rather annoying problem.

The AC keeps cutting out. It will run fine for a few hours then cut out. Sometimes, if it is working and I shut down the truck it can take a few hours to get the air working next time I start it. It also tends to shut down when running below 55.

One shop "fixed" it, said it was low on coolant. It worked for a day or two, did the same thing.

Another shop said that the expansion valve was freezing up and needed replaced, they did not have one.

Took it to another shop. They said it needed harness and a drain line, there was a service bulletin on it. They did that job. Same thing a few days later.

Any ideas? Could it be that expansion valve? It works good when it works. Cold and drops the humidity find.

Your truck is starting to sound possessed.

 

[ConfusedMuse]

Have you had it diagnosed... have the electrical system jumped, and if it keeps running it's a electrical problem, if it quits its a mechanical problem. Can you take it to a repair shop or someone who deals in your brand, or someone you trust not to 'fix' what they think is wrong but really fix it.

 

[blackpup]

Sorry, I was trying use the radiator as an example of heat exchanging device,not functioning properly .

jimmy

 

[layoutshooter]

He is talking about a part of the AC unit that is like your heater core.

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Yeah, I understand, I just don't know where to go with this. I feel like all I am doing is spending a LOT of money for people to guess at what the problem is.

 

[layoutshooter]

Sorry, I was trying use the radiator as an example of heat exchanging device,not functioning properly .

jimmy

I got it. I am slow for sure. I am not the most mechanical person in the world.

 

[mcavoy33]

Yeah, I understand, I just don't know where to go with this. I feel like all I am doing is spending a LOT of money for people to guess at what the problem is.

About 3 posts ago, I was going to say, it sounds like your wasting a lot of money on labour. At some point, you just have to say f it and decide that its cheaper to bulldoze the whole thing rather than finding a needle in a haystack.

aka replace the whole system

 

[blackpup]

Yeah, I understand, I just don't know where to go with this. I feel like all I am doing is spending a LOT of money for people to guess at what the problem is.

Yeah I know that feeling, money vanishing into thin air for nothing.

jimmy

 

[layoutshooter]

About 3 posts ago, I was going to say, it sounds like your wasting a lot of money on labour. At some point, you just have to say f it and decide that its cheaper to bulldoze the whole thing rather than finding a needle in a haystack.

aka replace the whole system

The entire system? I think I might try one more shop first. There is no way I can afford to replace the system. I will have to do without first.

 

[davekc]

Could be a couple of things, but most can be eliminated by the process of elimination.

You know the compressor is working if parts are freezing. That is one. At idle or moving slow, is the engine fan running? If not, that would likely be a air leak. It must draw air over the condenser to cool.
If that is ok but it is freezing, ensure shortly after start up that condensation is dripping on the ground.
Freezing can be a sign of low freon or two other things. Expansion valve is sticking or cracked, or the high side pressure switch is bad or there is a wiring problem to it. A meter test will show if there is a resistance or sensor problem. Those would give you the freeze up conditions and quick cutout you described. I wouldn't replace the whole unit.

 

[Slacktide]

Layout, We have had a couple of issues with the AC in our truck. From what it sounds like the tech's have run the gamut chasing this problem for you. For what it is worth here is my "2 cents".

First time we had an issue it was intermittent the AC would work great and then is was as if the compressor clutch would "wig out" and the system would blow warm then come back to life. The issue ended up not being the compressor/clutch it was actually a partially broken wire going to the low pressure switch that is in the hard line. When the system sees the pressure drop off it disengages the clutch as a protective measure. Once the wire was repaired the system worked flawlessly. Repairs were performed by Freightliner in Jefferson GA their tech had it fixed quick.

The 2nd issue we had recently was it was blowing warm while sitting or at low speed, worked better at highway speed. I was able to get it to work better while sitting ( in traffic or parked) by engaging the manual engine fan switch to draw more air over the condenser. this time it was a bad high pressure switch in the hard line. repairs done by Stoops Freightliner in FT Wayne.

I hope this helps.

 

[jjoerger]

This may not make sense but on ours if the temp control knob (colder/warmer knob) is turned all the way to the left it blows out warm. Turn it three clicks to the right and it will freeze you out.

 

[layoutshooter]

The fan works. Also that entire assembly was just replaced a few months ago. It was leaking.

I like the ideas on those last two posts. They give me a shot as what to tell the next shop. Slacktides problems sound exactly like what I have going on.