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Over the Road A/C inop

Yahoo Message Number: 112581
New day, new problem. I checked out my over the road A/C today and noticed the magnetic clutch on the A/C compressor does not engage. I'm hoping it's a fuse someplace in the system. I see on some coaches there is an in- line fuse on on others there is a circuit breaker. Anybody have a clue where to look.

Frank
40" 01 Intrigue
Serial 11304

Re: Over the Road A/C inop

Reply #1 –
Yahoo Message Number: 112582
Are you sure there's refrigerant in the system? If there isn't, the clutch won't engage.

You can get a cheap gauge (attached to a refill can) at any auto parts store.

7
Tim Gerrity

Exploit the inevitable!

Re: Over the Road A/C inop

Reply #2 –
Yahoo Message Number: 112583
Have you checked the refrigerant level? Clutch won't engage if there is low r134a.

Dave Trotter
01 Intrigue 11215

Re: Over the Road A/C inop

Reply #3 –
Yahoo Message Number: 112584
I pumped two small cans into it before I realized the clutch was not working. That was when I stopped and took a better look at what was happening. and shut it down for the night.

Re: Over the Road A/C inop

Reply #4 –
Yahoo Message Number: 112586
Frank,
We had the same symptoms with our #11238. There is a thermostat in the evap coil under the front end of the coach. Easy to get to on ours. Two wires run to it, detach the wires and connect them together. If the compressor runs now, the thermo is bad. If that doesn't fix it, it will take some more diagnosing. Kevin Waite was the go to for me and he had the part. Easy fix.

Don Krahling

Re: Over the Road A/C inop

Reply #5 –
Yahoo Message Number: 112587
103 when we pulled into Cummins Albuquerque in July this year, to have some work done. OTR AC was working well when we pulled in.

4 hours later, and we're ready to go, and the OTR AC would not work, and now 113 outside. I got the tech off to the side and quietly asked him if he could think of anything he may have hit that could have caused the OTR AC to stop working? (We had front shocks put on, and then everything else should have just been the computer plugging in under the dash for some Jake Brake setting changes...) And he thought for a few minutes, and said 'No.'.

They offered to take a look at it, but we had a heavy thunderstorm heading in and were moving on up to Santa Fe Skies in Santa Fe - so I said no thanks, and headed on up North for the about 1 hour drive.

With the help of this board, and a few others, I spent two or so days trying to find what caused the OTR AC to stop working...

One of the tips from this board, was to check the wire going up to the compressor, to be sure it was still connected, and or not chafed and broken. Well, it was no longer connected. (Speculate several years earlier, that a mechanic was getting access to the area, and disconnected it. When he put it back on, he did not put the protected sheath sleeve over it, and dang if I missed this in my yearly close inspection of wires and hoses... Connected back up, and the AC runs fine...

Good luck to you on your hunt, and hope it turns out to be something simple like it was on our coach:)!

Best to you, and all,
Smitty
04 Allure 31017
04 Allure Sold to a nice new owner! Now enjoying a 07 Magna Rembrandt 45' ISX600 #6775
"We're ONDROAD for THEJRNY!" (Toad and Coach license plates, say Hi if you see us!)

Re: Over the Road A/C inop

Reply #6 –
Yahoo Message Number: 112589
Don, where exactly is that thermo valve you discussed. Can you see it from the drivers side front cargo hatch?

Re: Over the Road A/C inop

Reply #7 –
Yahoo Message Number: 112590
There is a single wire that plugs into the compressor. I don't know if that is what activates it. I did put a voltmeter on the plug and there was no voltage. Again I don't know if that is actuates the compressor or if it has another function. Spent a couple of hours putting in the rear vertical seal on the bedroom slide. PITA. Used soap and a water spritzer to keep it wet. Worked better after I did that. After you get it started in the corner, it goes easier. Doing the lower one tomorrow. Like I said, I'm learning. Broke, but learning.

Re: Over the Road A/C inop

Reply #8 –
Yahoo Message Number: 112598
The power wire going to the compressor is only "hot" when the pressure switch ('s) is satisfied. Normally it will have a low pressure & high pressure switch (some have 2 separate switches & some have a trinary single switch that does both high & low). If the refrigerant is low it won't allow the compressor to activate and same if the pressure gets too high it will shut it off.

My recommendation is unless you have the proper equipment to take it to a shop that does. I have spent the better part of my life working on refrigerant systems and some of the biggest hair pullers are in fact diesel pushers. What I do on every coach is first do a reclaim on the system to find out whats inside, meaning how much refrigerant. Then with that knowledge pull a vacuum on the system and see how it pulls down & how it holds. Now IF after the reclaim nothing came out or very little but pulled down hard on the vacuum, I know there's a leak but probably a pretty small one, so then I charge the system with Nitrogen and run the pressure up to around 300psi and go thru every fitting in the system spraying with soapy solution and look for the leak, and while doing this keep looking at the pressure and doing what I need to keep the pressure up where I want it. Find the leak, fix the issue, replace the receiver drier, expansion valve & vacuum the system hard & long, usually a 45 min vacuum or longer to get as much as the contaminates out as possible. Then it's a guessing game on what to start with on charge amount, normally on the pushers I start with 2 lbs. Once charged I start the coach and see what it's doing, IF the compressor doesn't engage then dig into the electrical and figure out why. Once the compressor engages then it's on to setting the charge based on the gauges using the chart for R-134A. Once pressures are within specs then go onto taking splits of air in versus air out and adjust charge until I get a minimum of 25deg split. This gets tricky if ambient temp is low, always better when ambient is above 65.

Good luck and don't overcharge!

Jim Lewis
Infinity Coach

Re: Over the Road A/C inop

Reply #9 –
Yahoo Message Number: 112600
Here is what went down at my end.

I just have a low pressure gauge. When I first hooked it up, the pressure read about 15 lbs. I put two 12 oz can in and as I was standing there, I noticed the compressor was not engaged. So I stopped the fill process. The low side gauge read about 60lbs. I have no ideal what is happening on the high side. Started the trouble shooting process. Verified there was no volts at that wire going into the compress and I'm trying to find where the "fuse box" is for the engine system. My coach has two, one for the chassis and one for the engine. The diagram for engine fuse box indicates there are fuses for the a/c system on it. Anyway still hunting for that.

Should I dump out some pressure? or is that not considered high without the compressor running.

01 Intrigue
11304

Re: Over the Road A/C inop

Reply #10 –
Yahoo Message Number: 112602
The high side and low side will be equal when the compressor isn't running. Pressure is temp sensitive

 

Re: Over the Road A/C inop

Reply #11 –
Yahoo Message Number: 112633
I recall touching a cheater wire from a 12v power source to the compressor clutch lug with the engine running.

If the clutch engages with that power, then the clutch is probably ok.

If it works, you could have a relay or a fuse that is the problem. A cheater wire from each might give you a clue if one or the other has failed. If neither of those have failed the electrical problem may be in the dash switching.

Or, you could be low on 134a.

Dean
95 Magna 5280