A/C clutch not working on F53 chassis dash.

[Kahoona]

Hi
Here is the problem: There is no drop in air temp at the dash vents in our 2002 Coachmen Mirada. The clutch on the compressor does not engage. One day I went to drive it and there was no cooling. It had sat for only a month or two.



Here is what I checked and tried.

Fuses under hood #'s 2 and 3.,
The clutch relay #2
"Freon" pressure is at 20 low side which should be enough to work. It had 30 in it when it failed and I let some out to see what would happen (yes dumb but ...).

There is power to the Vacuum mode switch ( the dial with Off/AC/Max ect) and the switch does energize the wire to the compressor.

There is no power to either wire on the Pressure switch near the dryer.I am grounding the other wire to chassis when checking.

If I apply power to the red wire with the white stripe on the pressure switch with a jumper to the battery the clutch engages and the compressor runs for a minute then quits. The temperature at the vent begins to drop before it stops.

The diagram shows a thermostat between the dash switch and the pressure switch but I can't locate it and I have never noticed any thermostatic action.

It is the Tempcon system with the single 3 dial control. No specific info is available in the owners binder.

Here is the Tempcon site for diagrams I used. The compressor is Ford.



Any suggestions on where to go next?

[Terryshirley]

Sure hope what happen to me doesn't happen to you. I went without freon since spring. N kept hearing this weird noise. Will the clutch was engaging but shouldn't have. So the clutch/AC compressor froze up and $ 1000 later I'm back in business. Good luck

[IBDAGRIZ]

I had compressor clutch issues on my Dodge. The clutch is magnetic/electric and would fail, causing it to not run the compressor.



On some it can be changed instead of doing the whole compressor, but depending on age, you might wanna swap it all out to be safe once you figure what it is.


Griz

[Kahoona]

Update
I decided to add R134 to bring it up to the correct amount to see if the compressor would run. Since I was not getting 12v to the vacuum switch I started the motor, set the air to max then applied 12v to the clutch while I added the R134. It will now continue to run but only reduces the temperature by six degrees. I connected a new manifold to check the pressure and sticky. tan goo spewed out of a loose connection. Excess lubricant or old stop leak from long ago? Should I blow it out and fill fresh? The high side fitting got hot. Tomorrow I will get the fitting I need to stop the manifold from leaking and get a good reading.

[THenne1713]

Suspicion is you are low on freon; When low on freon, also usually low on compressor oil, so low pressure switch keeps compressor off for protection

[Kahoona]

New info, couple of questions please?

New Info. Found the thermostat under other numbers. I ordered.

I got what I needed to make my new manifold work and got these readings.

System on, Compressor off:
Low side 90, High side 100
AC on compressor on
Low side 93 High side 100
Is this enough pressure to run the system or do I need to add.



I followed wires and located the thermostat. I had thought that it was a thermostat for cabin temp but it appears that it may be for detecting coil freeze up as it is on the air-box in front of the passenger foot-well. The wire from the control panel to the thermostat has 12v. The thermostat tests open circuit and no power comes out.It appears to have a thermistor tip inside the box and might have a sensor on one side too.I will try to get some of the numbers from it by taking the picture and adding contrast. If I bypass it the compressor comes on so 2 questions.
1- Am I correct that the thermostat should be closed (passing current) under normal circumstances?
2- Can anyone suggest where to get one and how to tell what I need since the numbers are gone?


Tanish brown appearance of R1e4 in the sight glass on the manifold. Is that the compressor oil or is that scum that must be purged out?



Any answers would be appreciated. I don't want to screw it up (more) so I ask. I know I an out of my element but if I want to use it I have to fix it. No money left after getting tires!

Thanks

[Bob Hyatt]

Originally Posted by Kahoona

New info, couple of questions please?

New Info. Found the thermostat under other numbers. I ordered.

I got what I needed to make my new manifold work and got these readings.

System on, Compressor off:
Low side 90, High side 100
AC on compressor on
Low side 93 High side 100
Is this enough pressure to run the system or do I need to add.



I followed wires and located the thermostat. I had thought that it was a thermostat for cabin temp but it appears that it may be for detecting coil freeze up as it is on the air-box in front of the passenger foot-well. The wire from the control panel to the thermostat has 12v. The thermostat tests open circuit and no power comes out.It appears to have a thermistor tip inside the box and might have a sensor on one side too.I will try to get some of the numbers from it by taking the picture and adding contrast. If I bypass it the compressor comes on so 2 questions.
1- Am I correct that the thermostat should be closed (passing current) under normal circumstances?
2- Can anyone suggest where to get one and how to tell what I need since the numbers are gone?


Tanish brown appearance of R1e4 in the sight glass on the manifold. Is that the compressor oil or is that scum that must be purged out?



Any answers would be appreciated. I don't want to screw it up (more) so I ask. I know I an out of my element but if I want to use it I have to fix it. No money left after getting tires!

Thanks

low 90 high 100 is odd. Typically those pressures will equalize when sitting with compressor off. the 93/100 is broken. Are you sure the compressor is running? You should see something like 30-40 on the low side, high side will vary with ambient air temp inside and outside, but should be above 200 most of the time. But the killer is the low side. That low side directly affects cooling as the lower the pressure, the lower the temp at which the R134a boils and the greater the cooling effect you get. If the compressor is on, those pressures suggest that you might have nothing in the system but air. Which won't compress, liquify, boil off and provide any cooling. Or it might suggest that the compressor is shot, whether it is the reed valves or the pistons is a guess at best without hands-on.

[Kahoona]

Originally Posted by Bob Hyatt

low 90 high 100 is odd. Typically those pressures will equalize when sitting with compressor off. the 93/100 is broken. Are you sure the compressor is running? You should see something like 30-40 on the low side, high side will vary with ambient air temp inside and outside, but should be above 200 most of the time. But the killer is the low side. That low side directly affects cooling as the lower the pressure, the lower the temp at which the R134a boils and the greater the cooling effect you get. If the compressor is on, those pressures suggest that you might have nothing in the system but air. Which won't compress, liquify, boil off and provide any cooling. Or it might suggest that the compressor is shot, whether it is the reed valves or the pistons is a guess at best without hands-on.

I do know that there is coolant, cannot be certain how much but I believe it is close to the correct amount but not absolutely certain.



The clutch clicks and the center spins with the outer pulley. The engine does not react at all when it does kick in.



I need to figure out whether the compressor or clutch is shot or not. Regardless of the details I would then be able to attempt replacement. Is there anything else I can do to find out? In order to rule out contamination with air and over or undercharge, would it help if I emptied it, checked the coolant weight then drew a vacuum and refilled with the correct weight of fresh coolant? I assume I would add oil.



Thanks for helping me get closer to the answers.

[Kahoona]

Hi
Not sure where to go from here. Can anyone recommend a discussion board that covers Air Conditioning for RV's? I have done a bit of research but it is hard to tell what is next. Best I can guess would be to have the fluid pumped and then draw a vacuum and check for leaks. The dryer is not old but I could replace it too. I am assuming since no components were replaced I do not need to add oil. Once I add the correct weight of plain "freon" I should be able to find out if my compressor works. Does that make sense? If there is another source for info I will do what they recommend.

[JLWoodward]

On your thermostat you can search Evans tempcon and find a part number for it, common part. Yes shuts off system when it detects evaporator freezing up.

Tan gue in system is not good. Need to flush it. R134 wether it is pag 46 or 100 is fairly clear, light green if die added.

The tan gue is the result of moisture.

93 on low side is horrible, it's not drawing a vacuum, have blockage in the system or compressor is bad. Your clutch is good or at least working as it engages once you bypassed thermostat.

My recommendations for you.

Evacuate and flush all your lines and evap and condesor, blow compressed air through each line and component checking for restrictions. Flush with min spirits a few times as it's cheaper then one flush with isopropyl or lacquer thinner once.

Evap will of course need to remove orfice or the expansion valve depending which you have to flush it.

Fix issues noted above and reconnect everything.

Pull vacuum and check for leaks. Honestly compressed nitrogen is better imo for checking leaks I'll pressurise low and high side to 250 and spray all fittings, hoses, condesor, etc down with soapy water to leak check them.

Let it sit with press or vacuum for a day and see if it leaks down.

Before charging with freon replace the dryer and the expansion valve, and the faulty thermostatic valve

since flushed drain compressor oil and fill with correct amount for full system as system flushed. Charge with correct amount of freon

Note. If you found no restrictions when checked above, most likely compressor is shot, you'll need to access the value of your time versus the cost of compressor. I would recommend if no blockage found replace compressor before you recharge. Keep in mind if you go through all this and then run system to see if compressor is good or not. You'll need to reflush, and change dryer again when you take it back apart to replace compressor. Or you'll risk contaminating new compressor. This is just one of those things to better do right from the start or you'll cost yourself more in the long run.

[JLWoodward]

Here is your thermostatic saw p# for an Evans tempcon system

A46-3122-030

[rgmiller32]

The goo you are seeing is most likely the desiccant from the dryer that has failed. Has this system ever been serviced.

Sent from my SM-G930V using iRV2 - RV Forum mobile app

[Kahoona]

Originally Posted by rgmiller32

The goo you are seeing is most likely the desiccant from the dryer that has failed. Has this system ever been serviced.

Sent from my SM-G930V using iRV2 - RV Forum mobile app

Yes. Possibly not well though. About a year ago I had a cut hose. The system was empty. After repair I replaced the drier also. I drew a vacuum to 20 and checked for leaks. Then ran the pump again for an hour. I added 2.5 lbs of R134. It did work great for several months then the dash AC was not used for 2-3 months and stopped working.



There are some "buts" I did not know that the manifold hoses had to have the air let out when used and when the R134 was added. Humidity here in the keys is terrible.

That 2.5 was from the Tempcon site, I finally found the sticker and it should have been 2.75.



I did order a new drier when I got the supplies and I will replace it. That makes sense.



Should I add oil?

[Kahoona]

Originally Posted by JLWoodward

Here is your thermostatic saw p# for an Evans tempcon system
Attachment 208871
A46-3122-030Attachment 208872

Thanks. That probe goes straight in from the front of the box. I am hoping that I can get access to the fasteners that hold it from the vent on the front of the passenger foot-well. If not I may have to take the box out. It there were other diagrams there that might help could you please give me a link?



Thanks for your kind help. From the looks of it I will be having it emptied this weekend. I still need to swap driers and find out about the oil. My wife's Honda Civic just blew an o-ring on the condensor so I will be doing the same to that but that is simple. 2 for one!