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Topic: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good (Read 818 times) previous topic - next topic

Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Hey Y'all,

New Foretravel owner here, my wife and I just bought a 1997 U320. We have had a few issue with it, most were obvious fixes. This one is a bit odd to me. When we try to use the dash AC  the compressor doesn't kick on at all. I imagine its something to do with the AC selector switch or a relay somewhere? I'm an engineer and can figure out most problems but this one is a bit odd to me. Wondering is you all have had a similar issue and what the fix was? For now we are more than excited to own this coach and consider it quite a blessing to have found one in great shape for the year.

Thanks,
Tyler
Tyler & Morgan Baumgardner
Follow our journey, @Travel Baums on Facebook and Instagram
1997 U320 40'
Cummins M11 450 HP

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #1 –
Welcome! Does it have enough Freon in it? Try jumping the low pressure switch and see if it will run. I did that with mine when the compressor would not come on and that was my issue, low Freon, added some but it leaked out slowly again.
The selected media item is not currently available.Keith & Jo
2003 U320T 4025 PBBS Designer series
Build 6203    Cummins 500hp
2000 U320 4010 WTFE / Build 5762 —Sold—
Motorcade #18070   
Pasadena, Texas
2015 Jeep Wrangler Sahara-Sunset Orange pearl coat
Don't argue with a fool, people watching might not be able to tell the difference.

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #2 –
First thing I would do is use a set of AC gauges and see if you have freon,if you have some freon the compressor may be tripped on
low pressure cutoff,do that and go from there,too many variables to speculate until you check,you can also check with a volt meter
if the compressor is getting voltage.Do some checks and get back to us.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #3 –
First get a voltmeter to check the voltage at the dash control. If the voltage appears to be good then check the voltage at the compressor. It's possible that there is a low-pressure cut-out switch that is off because the refrigerant is too low. This coach should use R-134a refrigerant.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #4 –
Quote from: tyandmogo –
or a relay somewhere?

Tyler,

Your compressor relay and breaker are located  on the isolator panel.  You will also find the breaker and relay for the condenser fan there. You should find this info on the B-2126 print if your coach came with the info books.

If you find that the alternator isn't working properly  it can be because OEM the sense wire comes off the breaker for the compressor. Several here have moved this wire to a better location.
Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #5 –
It seems that many of our dash A/Cs don't work because the R134 leaks out. You could just buy a couple of cans of 134 and a $15 charging hose. Hook it up to the low pressure port and check the gauge. If it reads low just keep adding refrigerant until the compressor starts engaging. You'll have cold air up there before you know it.
jor
93 225
95 300
97 270
99 320

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #6 –
Since you don't know the history and assuming there is no refrigerant in the system you should start with a vacuum pump to see if it will hold a vacuum. Adding any refrigerant into a system that mostly likely does have air in the system by now will cause high discharge pressure\temperature. If you don't have gauges Harbor Freight has a cheap set that is worth buying.
As a FYI my 2001 U320 didn't come with a low pressure switch only a high pressure switch located on the receiver\drier by the condenser. With your age of the coach I would just overhaul (go through) the entire system, that is what I did with mine and haven't had any issues in 4 years here in Arizona summers. Lastly don't assume your system have the correct parts to begin with, I've seen many systems here autos and RV's with the wrong compressor, driers, O-rings and  Butcher up electrical.
Good luck, Steve
2001 U320 40' IF$ Build #5798
2018 Jeep Grand Cherokee Trailhawk Toad
2015 GMC Duramax HD2500 Toad
2014 Polaris RZR 1000
Litchfield Park, AZ- Soon to be Paulden, AZ

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #7 –
Quote from: Willy White –
Since you don't know the history and assuming there is no refrigerant in the system you should start with a vacuum pump to see if it will hold a vacuum. Adding any refrigerant into a system that mostly likely does have air in the system by now will cause high discharge pressure\temperature. If you don't have gauges Harbor Freight has a cheap set that is worth buying.
As a FYI my 2001 U320 didn't come with a low pressure switch only a high pressure switch located on the receiver\drier by the condenser. With your age of the coach I would just overhaul (go through) the entire system, that is what I did with mine and haven't had any issues in 4 years here in Arizona summers. Lastly don't assume your system have the correct parts to begin with, I've seen many systems here autos and RV's with the wrong compressor, driers, O-rings and  Butcher up electrical.
Good luck, Steve

He did mine also and it is still going strong!! think its going on 2 yrs now.

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #8 –
Who did yours?
The selected media item is not currently available.Keith & Jo
2003 U320T 4025 PBBS Designer series
Build 6203    Cummins 500hp
2000 U320 4010 WTFE / Build 5762 —Sold—
Motorcade #18070   
Pasadena, Texas
2015 Jeep Wrangler Sahara-Sunset Orange pearl coat
Don't argue with a fool, people watching might not be able to tell the difference.
 

Re: Dash AC Blows Hot Air, AC compressor is not engaging at all but looks good

Reply #10 –
Agree with Jor, on my 99, the binary switch on the receiver/dryer was a high/low pressure one.
Put a Autozone gauge/charger on low side, if it reads above 5 lbs or so, you should have some freon left in system. pull trigger and low side should go up enough to engage clutch on compressor, if it does, add enough refrigerant so compressor stays running. If this works, use gauge to figure out how much pressure at your temp. to use. It will go faster if you do this at high idle. If this does not work, back to the drawing board.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.