Dash AC does not blow cold

Keith Anderson · 06-08-2009, 08:17 PM

Sorry to beat a hot dead horse, again.
2005 Itasca Horizon KD.
When I turn on Max A/C or just A/C, the blower turns on, I feel air movement, but no cold air.
I've read about the thermocouple, but in this case, the A/C compressor in the engine compartment does NOT spin when the front dash knob is set to A/C or Max A/C.
I think it's a fuse, but I cannot find a 12VDC fuse for the dash A/C.
I've looked in the external compartment under the drivers side, under the dash, in the power cord bin where the inverter resides and under the bed in the rear of the coach. The coach basement air works great.
Would anyone know where I might find it or have any other suggestion?
Thanks
Keith Anderson

CC38EL · 06-08-2009, 08:34 PM

I don't know if you have the Cat or the Cummins, but I had a similar situation. On my Cummins 8.3L ISC, the air conditioning compressor sits on the upper right of the accessory mount. It has ONE (1) wire going to it that has a connector about 8 inches down from the assembly. As a matter of fact, it's the ONLY wire I can see.

That connector corrodes and causes the compressor to not engage. I clean it about every 4 months or so and the air conditioning runs fine.

I also serviced my air conditioning with a do it yourself kit and put in air conditioning oil and freon.

You can get automotive kits that work on your coach.

Hope your solution is as simple as mine.

Keith Anderson · 06-08-2009, 08:54 PM

It's a Cummins 8.3L ISC also. We haven't had any problems with the dash A/C in the 3 years/25,000 miles that we've been driving, so I'll look at this first. It's always hard for me not to think the worst first and to keep it simple.
Thanks and I'll let you know.

CC38EL · 06-09-2009, 05:47 AM

Another thing to check, once you get your air conditioning compressor going, are the air conditioning condensor fans mounted to the outside of your radiator.

We went a long time without using the dash a/c. Those fan bearings seized up and when I did get the compressor working, I then had to replace the fans.

They are common electric radiator cooling fans and run about $65-85. If you need to replace them. Hopefully you won't have to.

Rudolph · 06-09-2009, 08:27 AM

Your compressor will not run if your pressure in your system is low. If you get too much freon you will blow a line some place. Check your pressure first and check for leaks. good luck Jim

Gary CA · 06-15-2009, 10:17 PM

Hi Keith~ The high pressure freon line my be burned. Check the AC hose line in the engine compartment. My hose was too close to the turbo and the line was burnt. The AC tech installed a splice couple and recharged the line. I resecured the line and have enjoyed AC for several years. good luck.

Keith Anderson · 06-15-2009, 10:58 PM

I'll check the AC line, but I think it's getting time to take it in to be looked at. I cleaned all of the connectors, (which weren't dirty or corroded), and looked the best I could in the engine compartment at the compressor, but it's pretty far back. I may need to acces the engine from the bedroom.
Thanks again for the suggestions and please keep them coming. I've got a couple of weeks before I bring it in.

DonGee · 06-16-2009, 03:51 AM

Just had mine serviced, Freightliner said it was a blown compressor, so took it to my local mechanic and they replaced a"shrader" valve and said it shoul be good to go. Will wait for Global Warming to kick in so I can test it.

Don, WIT 70041

Dmiles · 06-16-2009, 06:30 AM

I have the same problem, it's just that we never use the dash air. I didn't even know it wasn't working until I took it in for a state inspection and the mechanic just happened to try it out. I think he was trying to drum up more business, but at their labor rates I told him to just stick to the things that will keep me from getting my inspection sticker.

I did a little investigation, and if I short the contacts on the high pressure switch, the compressor kicks in, so I'm thinking it needs a freon recharge, but of course also probably has a leak somewhere. If we actually used it, I would put some time into it but since we don't it will probably wait until off-season.

Keith Anderson · 06-17-2009, 05:58 PM

Is the high pressure switch at the front of the RV or in the engine compartment?
Could you please describe it's size and how many wires are connected to it?
Thanks

Dmiles · 06-18-2009, 07:11 PM

Quote:

Originally Posted by Keith Anderson

Is the high pressure switch at the front of the RV or in the engine compartment?
Could you please describe it's size and how many wires are connected to it?
Thanks

On my rig, as you lower the "hood" on the front of the RV, it's to the left and just below the radiator cap. It has 2 wires, one green and one black, or dark brown.

CC38EL · 06-19-2009, 07:12 AM

Keith,

If you look on passenger side (more towards the center) of your vehicle where generator is, you'll see a big black box - toward the right of the box you'll see two A/C lines...one is small hose, one is large
hose...small hose is high side, the big hose is low side....that's where you fill your A/C. Should have access ports with colored caps.

In the small hose is where you'll find your pressure switch. Should have 2 wires going to it.

See if this helps finding that switch.

Keith Anderson · 07-23-2009, 10:55 PM

Well, I took it in and the culprit was the "Pressure Cycling Switch", which I think is the same as the thermistor. The part was $21.27 and the labor was 1 hour to diagnose at 54.50/hr and 5 hours to replace it at $109/hr for a grand total of $620.77. Ouch, but I'm cool. Thanks for everyone's help and input.