Dash A/C blowing warm air?

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Dash A/C blowing warm air?

June 14, 2012, 01:09:49 pm

The belt is intact. With the control set to Max A/C I notice the compressor clutch engages for about 20 seconds then releases for a minute or two, then repeats.
At that setting should it be engaged constantly?
Any suggestions?
We used the generator and roof airs on our trip into NM.

Re: Dash A/C blowing warm air?

Reply #1 – June 14, 2012, 01:49:29 pm

Dick,
It sounds like the unit is low in R134a (refrigerant). You may just need to add refrigerant, but a professional tune-up is better as the unit can be inspected for leaks and the correct amount of R134a can be put in the system. These units need to be run at least once a month to keep all lubrication in good order.
Peter

Re: Dash A/C blowing warm air?

Reply #2 – June 14, 2012, 02:15:25 pm

Ditto Peters comments, right on.
Dave M

Re: Dash A/C blowing warm air?

Reply #3 – June 14, 2012, 02:15:43 pm

The 'cycling' clutch is almost always a result of low refrigerant. Question is, where's the leak? Usually just filling the system will not cure the problem, it's only going to leak out again. You need to find someone with an electronic sniffer that can detect very small R134a leaks. Only then can you fix and fill the system and be sure it's a closed system. You don't need an RV service center for this. Any A/C certified tech can do this for you.

Re: Dash A/C blowing warm air?

Reply #4 – June 14, 2012, 03:15:12 pm

I had to replace the hose to my Condensation fan and that fixed my problem.... It gets lot of heat from the engine.

Re: Dash A/C blowing warm air?

Reply #5 – June 14, 2012, 06:52:57 pm

My clutch will not engage even when I jump the breaker. I am replacing the compressor with a new clutch assembly. The auto reset fuse/breaker located under the bed is bad also. Likely a result of the clutch or another failure. you may want to check the breaker they are only about $10.00.

Re: Dash A/C blowing warm air?

Reply #6 – June 14, 2012, 07:40:14 pm

On our 2003 the hose from the compressor to the condensor was leaking at the crimped fitting at the compressor, so I took it off and took it to an ac repair center and had a new hose made up as he said he could not crimp on a new fitting as it would leak, but had I still been working could have used a portable crimper ane put on a new end, as I had done it many times on other coaches, but now retired and did not have access to the company tool, it now works great

Re: Dash A/C blowing warm air?

Reply #7 – June 14, 2012, 08:15:10 pm

We experienced the same in our '03 back in 2008. In our case we weren't low on freon, it turned out to be the clutch (diagnosed/repaired in 2009). Has been working great every since.

Michelle

Re: Dash A/C blowing warm air?

Reply #8 – June 14, 2012, 08:27:17 pm

Quote from: philtravel – June 14, 2012, 06:52:57 pm

My clutch will not engage even when I jump the breaker. I am replacing the compressor with a new clutch assembly. The auto reset fuse/breaker located under the bed is bad also. Likely a result of the clutch or another failure. you may want to check the breaker they are only about $10.00.

You may want to check with FOT Parts and price a whole new compressor. We just replaced ours and the entire new compressor was only $70 more than the clutch assembly, $370 vs. $300. That is the least expensive A/C compressor or the five Foretravel used so I got lucky for once. My dash A/C was always pretty good but now it works great. FWIW

Re: Dash A/C blowing warm air?

Reply #9 – June 14, 2012, 08:32:42 pm

When at FOT a week ago, my dash a/c was goofy, only low speed fan, and not good control of the ducts, so had the shop get into it, they brought the man up from production who knows the system, took him about 15 minutes to fix the problem, he said a wire came off a connector, that connector just happens to be under the center access door, removed the false bottom, removed the BCM control, the smart wheel control and something else, then he had access to the wire he was after. Now how long would it take me to find that wire ? Felt much smarter having FOT fix it, charged 1 hour total, I just laughed

This is why I got rid of the MCI and bought something I could take to people who know the equipment. PTL
Cheers
Dave M

Re: Dash A/C blowing warm air?

Reply #10 – June 14, 2012, 10:27:26 pm

Quote from: Dave M – June 14, 2012, 08:32:42 pm

... This is why I got rid of the MCI and bought something I could take to people who know the equipment. PTL
Cheers
Dave M

If I want something done right, I try to find someone who knows how to do it.

Re: Dash A/C blowing warm air?

Reply #11 – June 16, 2012, 07:39:54 am

My problem is a bit different - the compressor clutch stays activated all the time, even with the "ignition" switch in the off position.

The wiring to the clutch is small and should not carry much current, but is there another relay inline somewhere between the dash switch and the clutch? I have not yet investigated the voltages at the dash switch to see if the switch is defective, but I will do so later today.

Re: Dash A/C blowing warm air?

Reply #12 – June 16, 2012, 09:16:30 pm

Duane,
If it's like mine, it's one of the standard auto-resetting breakers located in the engine compartment, on the forward engine compartment bulkhead, mounted with others on a small metal plate.
I've had more than one with contacts fused closed, therefore leading to constant current drain (AC Compressor clutch energized), even with the ignition switch off. I found my source of current drain by lifting a battery lead and heard the AC Clutch disengage. Traced the wires back to the bulkhead.
Neal

Re: Dash A/C blowing warm air?

Reply #13 – June 16, 2012, 10:20:19 pm

There is a bosch type relay that turns on the clutch for the compressor. Sometimes they were located behind the left rear wheel on the frame and other times on the bulkhead where the battery isolator is

Re: Dash A/C blowing warm air?

Reply #14 – August 15, 2012, 06:31:58 pm

Follow-up just to close this out.
Truck shop in Salem, OR diagnosed the cause as a failed compressor pump. They replaced the compressor and the receiver drier today and the operation is normal; in fact better than it has been for the 2 years we have owned this.
I'm not 100% sure it wasn't just the clutch though. The tech based his decision on the fact that the high pressure didn't go above 150 psi. Turns out the new compressor didn't either. A different tech installed the new unit and he thought it didn't go up to like 250 psi was because motorhomes have a constant fan blowing on the condenser. I don't know, but I'm glad they replaced the whole thing.
I am attaching a troubleshooting chart I got from them. Hope it might prove helpful to someone sometime.
Dick

Re: Dash A/C blowing warm air?

Reply #15 – August 15, 2012, 06:57:42 pm

The air conditioner compressor on our coach will definitely achieve more than 250 psi on the high pressure side. When we bought the coach two years ago, the dash air conditioner did not cool. I added a lot of R-134A and one container that included some kind of leak stopper. (Yes, I understand that experts discourage the use of such a product.) I could see that some refrigerant and oil were leaking near the compressor clutch. However, the leak appears to be minor. I added a bit of refrigerant one time since the initial charge. The system works pretty well. We do augment cooling with house air when temperatures are high.

If your system works with a high side of 150 psi, that's good. Ours runs higher pressure than that according to my measurements.

Re: Dash A/C blowing warm air?

Reply #16 – August 15, 2012, 07:09:23 pm

JD, does engine RPM influence that? Our measurement was at idle.
What temperature should I get from the dash registers when on Max A/C?
I got about 47, which felt awfully good to me.

Re: Dash A/C blowing warm air?

Reply #17 – August 15, 2012, 09:39:28 pm

Hi Dick,

I used to work on car A/Cs (but only for some of my special residential A/C customers) and I always looked for air temp in the low 40s in the recirc mode ("stick" thermometer in a dash vent at 30 MPH or so).....as a healthy system. I think with the number of cu ft in a MH, that 47F is pretty durned good. As a side note: Automotive A/C systems are essentially always condenser limited. That's why you will usually see a huge floor fan blowing into the condenser/radiator when a tech is servicing/charging an automotive unit in hot summer temperatures. The modern autos with their thermostatically-controlled radiator fans (MH's too, I suppose?) will yield a lot more cooling at idle speeds than in years gone by (ups the heat transfer across the condenser [which gets the benefit of ambient air before the radiator does, cuz it's in front]....... just like when you get your car moving). Also, re your question about increasing the rpms on the compressor increasing the high side pressure looking into that condenser.....yes, it will.

Glad you are drivin' cool again. 'Tis wonderful. A lot of us remember trips up "Cataflash's" Baker grade (before auto A/C) with the windows down and hot,dry wind blowing through the '41 Ford, or whatever. Methinks some things about the "good ol' days" weren't so good.

Regards, Ed S ..... a used FT owner, some fine day.

Re: Dash A/C blowing warm air?

Reply #18 – August 15, 2012, 10:26:48 pm

Dick,

I think I was running at idle when I charged the air conditioner, but I don't remember for sure. I may have been running on a high idle. Yes, the differential across the compressor will increase at higher rpm. I think I probably put too much R-134A in the system. However, nothing blew up and it has worked well during the two years since I charged it.

I think our dash temperature was in the 40's as measured at the coldest spot I could find with an IR thermometer.

We did have a brief failure of the dash air on our last trip. The system quit cooling about the middle of a hot day. After we had stopped for the day, I checked wiring diagrams and looked at the components in the engine compartment. I found that the connector to one of the pressure switches had come loose. The connector appeared to be in place, but it was not making contact. Simply pressing it into position with my hand fixed the problem.

If you are getting 47F air from the vents, you are doing just fine.

Ed,

On the bus style Foretravel coaches, the condenser is on the driver side near the rear of the coach. An electric fan attached to the condenser drives air across the condenser. The fan runs whenever the condenser clutch is engaged.

Re: Dash A/C blowing warm air?

Reply #19 – August 15, 2012, 11:13:08 pm

yup, the condenser fan motor died and the dash air temp would only drop to 65f, after new fan, temp droped to 47f
Make sure the fan is running and fins are clean.
Dave M

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