Community Forums

bigjon42 · 06-22-2019, 06:57 PM

My somewhat new to me 99 executive, dash a/c won't cool. It worked fine a month ago, last time I tried it. I have determined the compressor clutch is not engageing. Several posibilities, low freon(?), or fuse. I have checked the fuse in the front run bay, looks good. there is a relay in the rear engine run bay, drivers side. Do I just replace it ? There also shows on the wireing diagrahm a 20 amp a/c clutch fuse(?) in the same rear run bay. It does not look replaceable. Any help would be appreciated. Jon

8.3Oilbuner · 06-22-2019, 10:10 PM

Hi Bigjon42 and fellow Washingtonian. My guess that it could be low Freon. If the clutch is not engaging the low pressure switch on one of the A/C lines up in the firewall in gen. compartment is open. This happens when the system pressure drops and keeps the system from doing damage to the A/C compressor. A small and quick test is to start the engine and select A/C on the dash control. The pressure switch should be in the smaller high pressure line. You should see 2 connectors/wires to the switch. Have someone at the rear of the coach looking at the A/C compressor clutch. With a jumper wire connect one terminal to the other, this bypasses the low pressure switch, and see if the A/C compressor clutch engages. If it does, you are low on Freon. This would be the first test I would do if you know the compressor clutch fuse is good. Also before everything I just mentioned, check the connection to the A/C compressor clutch. Have read here about corrosion in that connection since it is in the engine compartment and can be exposed to water and corrosion. This would be the first step I would do. Just a couple of easy checks to see where you are in the diagnosis's of the system. Good luck!

bigjon42 · 06-23-2019, 02:35 PM

Thanks, will try test as you suggested. Will report back. Jon.

Dom · 06-23-2019, 03:36 PM

Quote:

Originally Posted by 8.3Oilbuner

Hi Bigjon42 and fellow Washingtonian. My guess that it could be low Freon. If the clutch is not engaging the low pressure switch on one of the A/C lines up in the firewall in gen. compartment is open. This happens when the system pressure drops and keeps the system from doing damage to the A/C compressor. A small and quick test is to start the engine and select A/C on the dash control. The pressure switch should be in the smaller high pressure line. You should see 2 connectors/wires to the switch. Have someone at the rear of the coach looking at the A/C compressor clutch. With a jumper wire connect one terminal to the other, this bypasses the low pressure switch, and see if the A/C compressor clutch engages. If it does, you are low on Freon. This would be the first test I would do if you know the compressor clutch fuse is good. Also before everything I just mentioned, check the connection to the A/C compressor clutch. Have read here about corrosion in that connection since it is in the engine compartment and can be exposed to water and corrosion. This would be the first step I would do. Just a couple of easy checks to see where you are in the diagnosis's of the system. Good luck!

That switch will be on the low pressure line, the larger of the two lines going to compressor

JNewberry · 06-23-2019, 03:42 PM

On my 03 Holiday Rambler the pressure switch is on the liquid line (smaller line). Amazing to me as a retired refrigeration mechanic. If you have a multimeter, with A/C off check for continuity across pressure switch terminals. If it reads open on ohm scale switch is open, needs more refrigerant. You on't need a helper to check it this way. Any RV owner should have a multimeter in their bag of tricks.

bigjon42 · 06-24-2019, 05:22 PM

So, I am an amateur when It come to electrical. I have a pretty good digital multimeter, but not totally sure how to read oms. so, with engine running , a/c off, ohmmeter should read ?? Help, Jon

JNewberry · 06-24-2019, 05:52 PM

Ohms always measures resistance, so always with power off. No reason to run engine. On OHM scale read across the two terminals (wires disconnected) of pressure switch. If it reads zero (or very, very low if meter not calibrated) switch is closed. If it reads infinity (or same reading on meter with the wires not touching anything), it is open.

**Spdracr39** · 06-24-2019, 07:35 PM

It is almost certainly a low freon condition but the real question is where did it go. Charge it back up with some dye and see where the leak is.

jsmmonaco · 06-25-2019, 02:04 AM

07 knight......our dash air blows cold when you first recharge it, then it gradually goes away...........i don't mess with it anymore, i fire up the genny and turn on the roof airs............keeps it pleasant.............we have tried the dye's, must be leaking freon from somewhere we can't see............at this point, we really don't care, as long as the roof top's work..................

153stars · 06-25-2019, 12:27 PM

Google how to use a multi meter. A $10. 12 volt Test lamp is also nice tool some time you will read 12v DC on a multi meter but won't have sufficient power for anything. Good for quickly testing 12v fuses in place.

bigjon42 · 06-25-2019, 05:04 PM

Thanks for the explanation on measuring ohms. I have a nice digital multimeter, and have been using them for 40+ yrs. But only for testing voltage, so my 'OMS' knowledge is lacking. Jon

bigjon42 · 07-11-2019, 10:15 PM

finally got back to it. Omes meter indicated open pressure switch(no Freon). Added 3 lbs of R-134a and viola ! Dash a/c now works like a champ. When I first tried the dash air in March after I purchased the RV, I was in Albuquerque NM, High elevation. It worked even though the R-134 was low because enough pressure was generated due to high ambient temp. (I think) . Any way, all is well for now. Yes, the old R-134 went SOMEWHERE, but I'm hoping it is a slow leak. Happy camper