Ivylog Posted June 20, 2021 Share Posted June 20, 2021 (edited) UPDATE: It’s working and the only difference is where I store it is 72 degrees currently. Moved the MH outside where it’s 85 degrees and the AC is working. More details in my post below. I’m not finding any fuses in the FRBox for the dash AC and I’m not getting a signal to the RRBox from the dash controller for the relay that controls the clutch on the compressor and to the fan on the evaporator…2 fuses on the board check good. System works well when I jumper 12V to the coil in the relay^^^, energizing the clutch and the fan. All functions on the 3 knob controller seem to work but no signal to the AC relay in the RRBox.. The function knob (Off, Max…….) appears to ground the 10 different wires connected to it… no 12V power to it. Various positions puts a ground to different wires… must be a relay box in the dash somewhere. Any one know the brand and model of the dash controller or wiring diagram? Probably the same system in 06-09 Sigs, Exe, Dynasty and the big Beavers. Edited June 21, 2021 by Ivylog Link to comment Share on other sites More sharing options...
Frank McElroy Posted June 21, 2021 Share Posted June 21, 2021 I think the file called Dash HVAC is the download you want. Link to comment Share on other sites More sharing options...
David Pratt Posted June 21, 2021 Share Posted June 21, 2021 There is no fuse for the Dash AC. There is a 30amp Circuit Breaker and is part of the chassis MUX system in the front run bay. The CB may be an auto resetting CB. When you find it check to make sure you are getting voltage into it as well as out of it. Most of the 12vdc systems go thru the Chassis MUX. Link to comment Share on other sites More sharing options...
Ivylog Posted June 21, 2021 Author Share Posted June 21, 2021 Thanks but fortunately I do not have the chassis multiplex! Link to comment Share on other sites More sharing options...
David Pratt Posted June 21, 2021 Share Posted June 21, 2021 If you do not have the Chassis Multiplex you are lucky. There is a row of circuit breakers mounted in the top of the Front Run bay and the 30amp circuit breaker may be located there. There is also a 20amp fuse in the RRB(rear run bay) located in circuit board #3 top center of the board. it is fuse F2 and marked AC Comp Clutch. Link to comment Share on other sites More sharing options...
Ivylog Posted June 21, 2021 Author Share Posted June 21, 2021 (edited) UPDATE: using the wiring diagrams Frank provided I traced out that a blue/white wire is the 12V to the RRBox even though I do not have the same switch. Cranked the MH up and went to put 12V to the blue/white wire. Signal light was on and clutch was engaged…AC working. I store the MH in our home and the MH bay is quite cool…72 degrees. Moved it out a couple hours ago as we are headed West this evening…85 degrees out. Apparently the dash AC thermostat will not turn on the signal/clutch until it is warmer than 72 degrees even though the Tstat is on max cold as I haven’t done anything to it since last night. Thanks everyone for trying to help! Still need to find the extra relay box my system has to have with such small wires. Edited June 21, 2021 by Ivylog Link to comment Share on other sites More sharing options...
Frank McElroy Posted June 21, 2021 Share Posted June 21, 2021 Dick - Thanks for the update. Glad everything is now working. Link to comment Share on other sites More sharing options...
Ivylog Posted June 21, 2021 Author Share Posted June 21, 2021 (edited) THANKS Frank for your link to probably 100+ pages of wiring info. Fortunately I once worked in electronics, decades ago, but following Monaco’s wiring diagrams is still a challenge. Edited June 21, 2021 by Ivylog Link to comment Share on other sites More sharing options...
Frank McElroy Posted June 21, 2021 Share Posted June 21, 2021 Dick, One thing comes to mind. I don't know about my '08 Dynasty, but my old gasser had an evaporator coil with a temperature adjustable thermostat. 72 seems way too high a setting for that thermostat. That thermostat compressor cutout is to keep the evaporator from freezing up. So, I'm sort of thinking that you might have had a stuck pressure sensor since in your previous post you mentioned that static freon pressures were good. BTW, with the AC now running, are the freon pressures reading good showing a full charge? It sounds like you now have a wiring diagram that's close enough. If you run into this problem again, by testing voltages, you can see whether the temperature or pressure sensor is preventing the compressor clutch from engaging when it should. Link to comment Share on other sites More sharing options...
Ivylog Posted June 21, 2021 Author Share Posted June 21, 2021 I bypass the freeze sensor (put a fuse in the 2 wire) so the compressor runs all the time. Out West it takes 6+ hours before the air flow decreases…turn the AC off and still get cold air as the ice melts…takes about 15 minutes and the turn the compressor back on. We rarely have to run the generator and roof AC with just 2 people up front. Link to comment Share on other sites More sharing options...
Frank McElroy Posted June 21, 2021 Share Posted June 21, 2021 Well, now I'm confused. Your last post said that you bypass the evaporator freeze sensor. So how is it that when you moved the coach outside and the temp was above 72 the AC compressor engaged? If bypassed, why would changing the ambient air temp make a difference? Or maybe in your current location it isn't bypassed. Link to comment Share on other sites More sharing options...
Ivylog Posted June 21, 2021 Author Share Posted June 21, 2021 Hey, I agree this doesn’t add up and to begin with I thought it was low on Freon but with a 30lb tank hooked to the low pressure side it never started the clutch and the hose from it didn’t get cold… very little Freon going in. That’s when I put a pressure gauge on and static pressure was 90+ psi. Time will tell. Link to comment Share on other sites More sharing options...
Frank McElroy Posted June 21, 2021 Share Posted June 21, 2021 Hmm - Yes, it isn't adding up. Do you have a trinary pressure valve that also operates a condenser fan behind the front axle? It might be a sticking valve especially if the high and low AC operating pressures are OK. Link to comment Share on other sites More sharing options...
Ivan K Posted June 21, 2021 Share Posted June 21, 2021 Pressure switch can go bad too, I had one recently fail on my car. If in doubt, you can bypass it too, for test. If ever a stop leak was used, even more possible. Link to comment Share on other sites More sharing options...
Frank McElroy Posted June 21, 2021 Share Posted June 21, 2021 Good point. That is the main reason I never use stop leak! 1 Link to comment Share on other sites More sharing options...
Ivylog Posted June 22, 2021 Author Share Posted June 22, 2021 (edited) 600 miles and still working…40 degrees different Edited June 22, 2021 by Ivylog Link to comment Share on other sites More sharing options...
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