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khodgens · 07-17-2022, 11:52 AM

03 Monaco LaPalma gas, dash air is warm. Checked r134 and shows 45lbs which is good. It appears the compressor isn't kicking on and would like to know if there's a relay that's possibly bad. PO had it serviced because it was low on r134 and it cooled for about 20 minutes then went warm. Looking for suggestions. TIA

Ray,IN · 07-17-2022, 12:20 PM

It is quite possible the electric clutch has failed.

This may prove useful: HD air conditioning service manual Yes there is a relay, see page 34.

code2e · 07-17-2022, 12:57 PM

Quote:

Originally Posted by khodgens

03 Monaco LaPalma gas, dash air is warm. Checked r134 and shows 45lbs which is good. It appears the compressor isn't kicking on and would like to know if there's a relay that's possibly bad. PO had it serviced because it was low on r134 and it cooled for about 20 minutes then went warm. Looking for suggestions. TIA

R-134A has a pressure / temperature relationship. 45 psi would be correct at 49 degrees F. Is it that cold there? Sounds low on charge to me. May well have air (moisture) in system if it ran empty before and was just charged.

At a minimum, system should be evacuated and held under vacuum for 30 minutes. That will remove the air and boil out moisture. Then it will be possible to charge to the proper amount with dry R-134A.

The compressor clutch is cycled on by a pressure switch. That switch may control a relay to carry the current, or may switch the clutch itself. Either way, the pressure needs to be correct to operate the switch.

You may be able to rent a gauge set and vacuum pump from a tool rental or a large auto parts store if you want to do this yourself. The more vacuum time, the better.

donr103 · 07-17-2022, 01:13 PM

1st.. you don't measure low side pressure.. if compressor is not running.. so sorry your measurement means nothing.. Are you planning on doing the repairs yourself ? Or shop?
2nd.. you need to get a basic automotive a/c repair book.. a/p store will have or favorite online store. Even if you don't plan to work on it.. yourself.. it may save you from being ripped off.. makes great addition to the rv library..

So how old is compressor ? It must be running to get measurement on low side..
Good luck and keep us posted

khodgens · 07-17-2022, 02:23 PM

I'm sorry I should have explained further. I'm 74 done my own repairs most of my life but since the NM fires destroyed our home. everything in it including a 50 year accumulation of tools and parts I suddenly find myself w/o even the basics right now. Since it was charged up at a shop 3 weeks ago and then went warm after cooling for 20 minutes, I have the belief it could possibly be something simple. Hense a pressure switch. We're currently forced to live in it so putting it in a shop at this time (the best choice) simply can't be done at this time. Thank you for all the good information!

code2e · 07-17-2022, 03:09 PM

Quote:

Originally Posted by khodgens

I'm sorry I should have explained further. I'm 74 done my own repairs most of my life but since the NM fires destroyed our home. everything in it including a 50 year accumulation of tools and parts I suddenly find myself w/o even the basics right now. Since it was charged up at a shop 3 weeks ago and then went warm after cooling for 20 minutes, I have the belief it could possibly be something simple. Hense a pressure switch. We're currently forced to live in it so putting it in a shop at this time (the best choice) simply can't be done at this time. Thank you for all the good information!

How did you determine the pressure in the system? It really does mean something because of the pressure / temperature relationship of refrigerants.

Do you know if shop evacuated system, or did they just add R-134A?

It is possible there may be mobile service available in your area. Very little equipment is needed to service chassis A/C and its all done outside, up front. No reason you can't live in coach while A/C repaired. Maybe another RV'er nearby has a reference for you?

If I knew your chassis mfg., engine size and make of dash unit, I would try to get you a location & part number for the cycling pressure switch. They do fail, fairly inexpensive and you could try that if you wanted.

donr103 · 07-17-2022, 05:22 PM

Sorry for your loss.. I lost my home in real estate crash of 08.. hopefully you had home insurance and fed disaster relief.. I had nothing with wife and 2 daughters.. one with terminal brain cancer..
All that aside.. I need to know how old a/c compressor is??

153stars · 07-17-2022, 05:29 PM

Like said 50 psi static pressure is too low if hot enough to want AC. Normally I would say to start over. But a couple of cans to trigger the pressure switch to at least tell you if compressor and switch/s work. You can jumper the switch to see if compressor is working.There are a few pressure charts out there to MH ACs that will get you close. The little pressure to temp gauge on DIY can will most likely put you at over charged with MH system and thermal expansion valve.

FloridaSon · 07-17-2022, 05:34 PM

Quote:

Originally Posted by khodgens

. Since it was charged up at a shop 3 weeks ago and then went warm after cooling for 20 minutes, I have the belief it could possibly be something simple.!

I have a simple thought. My dash AC would start to get warm after about an hour driving. One time I took it into the dealer for something else and after about 45 minutes, we looked into the front where the AC box was located. There was water pouring out of a corner of the box. The service tech said that water was retained because of a vacuum created in the box when the AC mode was set for recirculate. He said it got better when set to FRESH, the flow through air flow relieved the vacuum.

BUT, my thought is it iced up set on recirculate here in Florida heat and humidity. We all know cooling is reduced by icing up. By waiting 45 minutes the ice simply started to melt. So if I keep the AC on FRESH it may keep ice from forming.

Your issue may be similar and this may be something to try. Or at least rule out. I could not test my theory as I had to leave the coach at the dealership.

Hope this helps.

Onrecess · 07-17-2022, 07:15 PM

Freon only goes low because there is a leak. If you added freon and it went warm again it is probably out on low pressure. You can get a can with a hose at any auto parts. If it starts up, you have to get the leak fixed.

khodgens · 07-18-2022, 11:35 AM

We're not low on r134 and watching the cooling fans in front of the radiator it's rather obvious that the compressor isn't kicking in. We're in an extreme rural area along the Colorado New Mexico border. I'll try and get buy until we move in 2 weeks closer to Pagosa Springs Colorado. I think I know someone there that can diagnose and fix it. I'll a separate post on my gen issue. Thanks for the help and good advice.

garyw148 · 07-22-2022, 10:24 PM

I am having the exact same issue with my 2006 HR with the 8.1 workhorse. I had it evacuated and recharged today. The mechanic said his AC machine showed no leaks in my system. I will run it again tomorrow to test again. It did seem cooler when I drove it home but only warm air while just idling.
I will be interested in what you find. And if I figure mine out I will post here also.
.

code2e · 07-22-2022, 11:22 PM

Quote:

Originally Posted by garyw148

I am having the exact same issue with my 2006 HR with the 8.1 workhorse. I had it evacuated and recharged today. The mechanic said his AC machine showed no leaks in my system. I will run it again tomorrow to test again. It did seem cooler when I drove it home but only warm air while just idling.
I will be interested in what you find. And if I figure mine out I will post here also.
.

The dash A/C evaporator is mounted in the same box as the heater core. There is a temperature door that directs the airflow thru either or both. If that door is blocked or mis-adjusted, some hot air mixes or even takes over the air coming out your vents.

If you look up the manufacturer of your dash unit, you should be able to get at least a parts diagram off their website. Maybe a trouble shooting guide. Check the door for fully closing off hot air.

As a quick check, you could pinch close a heater hose temporarily. Keep out hot water and see if A/C stays cold.

Many large trucks have summer shutoff valves installed to insure colder A/C.