A\C Problems

[garylmoore]

I parked the truck about 3 weeks ago to change the drivers side mirror. The heater element had went out on the mirror and I wanted to change it before winter came around again. . I changed it out, put my door panel back on and thought all was ok.
It was ok, with the door windows and mirror, but when I went to turn on the air the blower motor fuse in the dash was blown.
And no, when changing the mirror, I did not disconnect the batteries, but didn't really see the need with it being plug in connectors. Also, if there had been a short, wouldn't any fuse that blew be the window or mirror fuse?
I replaced the fuse which solved the fan problem and tried the A\C, nothing but hot air. I checked the compressor clutch, it was not moving.
The air was working when the truck was parked. I pulled the clutch fuse under the hood and it was intact. I swapped the A\C Relay with the horn and it made no difference.
I have had the truck 3 years and have not had problems with the air before now. I find it hard to believe I lost the refrigerant after only three weeks of sitting. I have the correct gauge setup for checking the refrigerant, but not sure what kind of reading will tell me if I have no refrigerant.
So, what is my next move here?
I know the clutch will not activate without refrigerant in the system, should I try charging the system to see if it comes on? I have R-134A, dye and a blacklight to check for leaks.
Pull the electrical connector on the clutch and see if the clutch has power?
If I crawl under the truck with channellocks and try turning the clutch, will that tell me if the compressor is locked up?
Any and all comments will be appreciated. Thanks .. Gary

 

[jffmaz]

Your could try jumping the low pressure switch and see if the compressor clutch kicks in. That would confirm low gas (or bad switch) IF it works. If not, try rotating the clutch plate as you suggested, then check for power at the compressor clutch as you said. While you are there, check the ground circuit at the connector - clutch coil is grounded through the connector, not the body of the compressor. Try everything before dumping a bunch of garbage into the system, stop leak, etc. Look for oily dirty connections for leaks first.

 

[garylmoore]

Yeah, not going to put anything into the system but refrigerant and maybe a little oil. I will try jumping the low pressure switch as you suggest. Thanks much for replying. Gary

 

[JR]

I would put your gauges on first before jumping the compressor - if for some reason it did leak out you don't want to run the compressor dry. I'm going by memory and could be wrong but I think the low pressure switch is set around 20 psi. Your static pressure should be well above that.

 

[garylmoore]

I would put your gauges on first before jumping the compressor - if for some reason it did leak out you don't want to run the compressor dry. I'm going by memory and could be wrong but I think the low pressure switch is set around 20 psi. Your static pressure should be well above that.

So, low side should be above 20+ psi? Thank you for the reply. Gary

 

[garylmoore]

I would put your gauges on first before jumping the compressor - if for some reason it did leak out you don't want to run the compressor dry. I'm going by memory and could be wrong but I think the low pressure switch is set around 20 psi. Your static pressure should be well above that.

I put the gauges on and had about 55 lbs static in the low and high side both, that means the compressor not cycling was not from lack of pressure, correct? I take it I need to check the low pressure switch? That goes into a plastic conduit on the firewall, it may come out at the big connector about 2 feet away, but not sure. Any easy way to check that you know of?

Also, when I pulled my gauges, the high side valve stuck and I could not get it to stop venting.
So it looks like I am going to buy the tool and valve core and change it. I would have the refrigerant recovered, but it is probably all vented by now. I cannot jump out the low pressure switch unless I fill the system again after I change the valve cores, correct?

Regardless, whatever has to be done, I will recharge and add dye to the system. Should I put a little A\C oil in there with it, or not? I have the proper stuff. Gary

 

[JR]

55psi should have been more than enough to activate the compressor. Pulling a vacuum will not remove enough oil to be concerned with. Generally not necessary until you start replacing components.
When you add freon off a vacuum the system will take enough that it SHOULD cycle on its own. Definitely don't jumper anything until you get some freon back in the system.

 

[garylmoore]

I will not run the compressor without refrigerant, but if I fill it to check the switch and have to replace the low pressure switch then I will lose all I put in there to check its' function. Can I check voltage on the low pressure switch with the car running and A/C on and if voltage is present, know my switch is bad? If so, would that be 5 vdc or 12 vdc? Hmm.. but that will not help if I have a bad ground.. What if I jumper it, watch the clutch closely and pull the jumper as soon as I see the clutch turn (if it does). Or will checking for resistance on the switch give me a clue to its health?
I have the valve cores ordered, they should be here Monday. I am going to replace both high and low side.

 

[petersonj]

If this were my truck showing a static gauge pressure of 50 psi., I would just jump the low pressure switch to see if the compressor kicks on. The compressor only needs to run a moment for verification. I can't see see how the compressor would be harmed for that moment. If it does not kick on, then you know that you have a problem elsewhere.

- John

 

[garylmoore]

Well John, that was the plan until the high side valve stuck open and dumped the pressure when I removed the hoses. That's why I am replacing the valve cores. I will do a momentary check with zero pressure if I am told it is safe to do so.. If not, I will either find a way to check the signal to the low pressure switch or fill it again and have it vacuumed if the low pressure switch needs replaced. Gary

 

[jffmaz]

The cycling / low pressure switch is on the accumulator. It can be removed / replaced without losing gas - the accumulator has a schrader valve under the switch

 

[garylmoore]

The cycling / low pressure switch is on the accumulator. It can be removed / replaced without losing gas - the accumulator has a schrader valve under the switch

Ah.. you pull the switch and the valve closes! Well that is a good thing to know! Thank you for the information. I guess it is safe to recharge!

 

[garylmoore]

Ok.. I will have the new schrader valves Monday and continue the repair. Thanks to all of you for the great information!

 

[petersonj]

Well John, that was the plan until the high side valve stuck open and dumped the pressure when I removed the hoses.

I missed that on my first read. If your high pressure side valve looks like mine in the above photo, there is an inherent design flaw. The rubber seal likes to dislodge when disconnecting the high pressure quick-connect. I installed a new one on my truck because the old one failed in the same manner as yours. The new one did the same thing when I disconnected the quick-connect the first time. I was not happy. I had to recover the refrigerant and when the system pressure became equal to atmospheric pressure I was able to push the seal back into place. I did not reconnect the high pressure hose for recharging. I now only use the high side connection when absolutely necessary because I am afraid it will happen again.

You don't need the the high pressure hose connected to the system to recharge with new refrigerant. You may want to consider that option if you have concerns regarding the high pressure connection.

- John

 

[garylmoore]

I did not notice the seal being dislodged, I will look tomorrow. This seal is in the Schraeder valve itself? I poked around on it to try to get it to reseal when it first happened, but no matter what I did it continued to leak. I figured it was contaminated and being held open by something. I bought 2 new OEM Schraeder valves, so they are going in regardless.
I believe I charged the system when I first bought the truck 5 years ago and it was not an issue at that time. At this point I do not know the reason for the compressor clutch to fail to pull in, hopefully it is something easy. Thank you for the heads up! Gary

 

[garylmoore]

View attachment 128574


I missed that on my first read. If your high pressure side valve looks like mine in the above photo, there is an inherent design flaw. The rubber seal likes to dislodge when disconnecting the high pressure quick-connect. I installed a new one on my truck because the old one failed in the same manner as yours. The new one did the same thing when I disconnected the quick-connect the first time. I was not happy. I had to recover the refrigerant and when the system pressure became equal to atmospheric pressure I was able to push the seal back into place. I did not reconnect the high pressure hose for recharging. I now only use the high side connection when absolutely necessary because I am afraid it will happen again.

You don't need the the high pressure hose connected to the system to recharge with new refrigerant. You may want to consider that option if you have concerns regarding the high pressure connection.

- John

That piece of rubber was rolling around in my Schrader valve also, got a pick and pulled it out.
I ordered parts from Dodge and they gave me the wrong ones. $45 for two valves that looked like they belonged in a bike tire but mine had a replaceable cartridge. The Cartridge was unavailable from Dodge as was the entire AC line. I found the cartridge at Napa for $5.

 

[garylmoore]

This morning I replaced my bad Schrader valve, then vacuumed the A/C system. the vacuum held for a half hour with gauge valves off.
Ok, since the compressor is not compressing and I was told not to try to run the compressor without refrigerant, I put in about a half a can of refrigerant into the low side (static) after disconnecting the vac pump. My gauge is sitting at 60 lbs right now. Is it ok to try to troubleshoot the compressor now? Should I try to add the rest of the can first?
Thanks.

 

[garylmoore]

Well, I became impatient, started the truck up, turned on the a\c and the compressor came on. I had put about a half or a small can in, finished up with three cans total. When I looked at the temp the last time it was about 47 degrees coming out of the dash vent with the control on Max A\C.
Something strange though at the end of the charge, the system stopped cycling. I have never seen the gauges not cycle.
Still cooling though. I took the truck for a ride and was 37 degrees in the center vent, outside temp was 82 and very humid. I would be thrilled if this is normal and y'all feel that non cycling thing at the end of the charge was not unusual.
The only thing I did to make the compressor start up was change a fuse that was not blown and tested ok with digital meter and put refrigerant in the system. I did wiggle the fuse around going in, maybe those contacts need a good cleaning.

 

[jffmaz]

Did you finally put the full 32 oz in? what is the ambient temperature while you are doing this? What RPM is the motor running while it is not cycling? Max AC with fan on high doors open?
By not cycling do you mean it is hovering near 30-35 psi low side? By not cycling compressor not turning off or not turning on?
Ambient temp, engine RPM, fill quantity could easily make it hover at the lower end of psi and not cycle.

 

[garylmoore]

I put 36 ounces in total. Max air, doors open center vent had the thermometer. Ambient temp about 84. Yes, staying around 30 psi on the low side when not cycling. Compressor was not turning off, ran constantly on Max A\C. All this was happening at idle (about 700 rpm) while filling. So, am I ok here? It is for sure COLD and it held vacuum with both sides closed for a half hour, so there is no leak in the system.