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OTR A/C Compressor has no 12V to it

Yahoo Message Number: 105551
Hi All,

I discovered recently, during annual service, that the A/C compressor was not being energized when dash air was selected.

After a bit of diagnostic research with wiring diagrams and 12V test light, I determined that I had power to and from the A/C select switch, but I am trying to test downstream from there. The next item on the check list is a SPDT relay located "on front board front bay driver's side" to quote my wriring diagram. I was in that area this AM, but could not find anything I could identify as a "front board". I could not hear a relay activating when switching the A/C on/off.

What should I be looking for? Have any of you had a similar problem? How did you resolve it?

Any advice would be appreciated,

Don Krahling

36' '01 Intrigue #11238
Yuma, AZ

Re: OTR A/C Compressor has no 12V to it

Reply #1 –
Yahoo Message Number: 105557
Hi Don,

The first thing I would check are the A/C pressures. The A/C compressor clutch will not engage when the system is undercharged (to protect the compressor). You pick up a set of A/C gauges at Habor Freight for about $60-.
Bill

2003 Intrigue 11514

Re: OTR A/C Compressor has no 12V to it

Reply #2 –
Yahoo Message Number: 105558
Thanks Bill,

What is the regulating device for that? The trinary switch? I think I should be able to hear the relay I referenced in my last post activate/deactivate when I cycle the A/C switch on/off even if the trinary switch were not satisfied. ???

Re: OTR A/C Compressor has no 12V to it

Reply #3 –
Yahoo Message Number: 105563
1. You can get a set of gauges from AutoZone for free use. I did.
2. Without those there are other things you can do fairly quickly.
3. I assume you have already observed that your compressor clutch does not engage with the compressor when your AC switch is on.
4. Also, your condensor fans are spinning when the ac switch is on? If not check their fuse and relay.
4. Run a cheater wire from a 12v source to the compressor 12 v connector. That should cause the compressor clutch to engage.
5. If it does, you then need to see about about 12 dcv at the compressor clutch on the wire from the ac relay.
6. If you do not, bypass the relay and run a cheater wire from the ac fuse to the compressor clutch. If the clutch engages, find the relay in the front run box. ( Your cc manual will help you with the location.) 
7. If the compressor clutch still does not engage, get the gauges and check the system pressure. It does not take much psi to get the clutch moving.
8. Do an resistence test of the compressor at the connector. You should see from 2 to 5 ohms if the windings are good. Higher or lower is likely a problem.

Good luck 
Dean

95 Magna 5280

Re: OTR A/C Compressor has no 12V to it

Reply #5 –
Yahoo Message Number: 105565
The front board on my rig is a bunch of fuses that light up when energized in large box in the basement compartment under the driver's feet.

In that box also is a bunch of relays. Trace the wire from the fuse to the relay, or look up the wire number in your cc manua.

Re: OTR A/C Compressor has no 12V to it

Reply #6 –
Yahoo Message Number: 105568
Thanks to several of you that responded. I think my next test will be the static pressure of the system to see if there is enough pressure to satisfy the low pressure side of the trinary switch, and maybe bypass the trinary switch. I have to get the coach out of the garage a few feet to get into the engine compartment. I'll keep you informed.

Thanks again,
Don

Re: OTR A/C Compressor has no 12V to it

Reply #7 –
Yahoo Message Number: 105569
Don,

I had a problem like that. Turn on the AC and would not cool. Checked the compressor and it was not turning. Ran 12 v to the compressor and it came on so I know it was fine and I had plenty of freon in it.

Talked to Kevin and he helped me.

There is a resistor switch????, I think the one you are looking for, under the front of the coach. Thought it was in the compartment in front of the passenger seat but it was not there. About in the middle of the front of the coach, slide under there and look up. You will see the black AC housing and there could be a small box attached to it with two wires going to it and a long metal wire coming out of it. Kevin had me pull the two wires off the box and jump them together, bypassing the switch. When I did this the compressor came on. Kevin had the part in stock. It was some type of thermostat resistor.

Hope this helps and I have a picture of the part if you need it.

Richard Aquino
2001 Intrigue

Re: OTR A/C Compressor has no 12V to it

Reply #8 –
Yahoo Message Number: 105570
Don,

It's been a long time since I worked on the A/C. As I remember, when there is a call for A/C, power is sent to the trinary switch (located on the drier next to the compressor. If there is enough pressure to safely start the compressor (engage the clutch), the trinary switch will send signal to the relay (located on my Intrigue under the dash on the passenger side). The relay will send power to the compressor clutch. When the pressures reach a certain level, the trinary switch will send a signal to another relay (located next to the one above). This will make the relay send a signal to the fan controller, which will have the fan go to a preset speed (I think its a medium speed). The fan helps cool the condenser which brings down the high side pressure. I moved my drier and trinary switch from the back (next to the compressor) to the front (next to the evaporator). This saved me approx. 20 feet of high pressure hose. I also insulated the entire low pressure hose.
Remember, I did this a few years back, so you might want to check your wiring diagram. Or let me know and I'll look it up.
Bill

Re: OTR A/C Compressor has no 12V to it

Reply #9 –
Yahoo Message Number: 105575
Thanks, Bill and Richard, for the helpful info. Richard, I would appreciate the photo. Email me at: donkrahling@...

My next steps in the diagnosis, involves pulling the coach out of the garage a few feet that I might get into the engine compartment. Maybe this weekend.

Don

Re: OTR A/C Compressor has no 12V to it

Reply #11 –
Yahoo Message Number: 105581
donkrahling at g mail dot com

All connected in the normal manner of course

Don

Re: OTR A/C Compressor has no 12V to it

Reply #13 –
Yahoo Message Number: 105583
Pull off the connector and jump the two wires together, thus bypassing the switch. If the AC compressor comes on that was your problem.

I was scratching my head thinking I would have to find a broken wire and Kevin put me right on it.

Richard

Re: OTR A/C Compressor has no 12V to it

Reply #14 –
Yahoo Message Number: 105584
Let me restate this.

You have to first turn the AC on. Remove the connector in the picture and jumper the connector. If the AC compressor comes on then this (item/switch/thermostat) in the picture is your problem.

Richard

Pull off the connector and jump the two wires together, thus bypassing the switch. If the AC compressor comes on that was your problem.

I was scratching my head thinking I would have to find a broken wire and Kevin put me right on it.

Richard

Re: OTR A/C Compressor has no 12V to it

Reply #15 –
Yahoo Message Number: 105597
Thanks for the photo Richard. And thanks also to the rest of you for the helpful input. The first thing I will check is the item Richard sent the photo of and then go from there. Don

Re: OTR A/C Compressor has no 12V to it

Reply #16 –
Yahoo Message Number: 105639
Thanks again Richard. Bullseye on the problem of the thermostat. I have a call in for Kevin.
Interestingly I found a second problem as I was checking fuses. The water circulating pump at the engine is leaking/shorted/blowing fuses. I'll talk with Kevin about that also.

Don Krahling

'01 36' Intrigue #11238

Re: OTR A/C Compressor has no 12V to it

Reply #17 –
Yahoo Message Number: 105656
Don,

A lot of people have had problems with the circulating pump (used for the OTR heater up front). I just bypassed mine with a hose connector on my 36 ft Intrigue. I still get plenty of heat up front without it.
Bill

2003 Intrigue 11514
 

Re: OTR A/C Compressor has no 12V to it

Reply #18 –
Yahoo Message Number: 105660
Thanks, that's good to know. I talked to Kevin on Friday, and that was his advice also since the pump costs big bucks. It's coming off tomorrow AM.
Don