Intermittent A/C issues-HELP!!!

[socalchuckster]

Ok, so I picked up my "new to me" 99 XJ a few weeks ago. XJ is really clean and I have been luck to have no electrical or engine gremlins, so far. When I checked out the XJ at the dealership and on the test drive I made sure the A/C was on Max high for about 20 minutes and it stayed cool. The next two weeks the A/C stayed cool with no problems at all. Now I've noticed that some times it works and other times it will blow hot or just outside temperature air. I am somewhat mechanical compliant, but am a little intimidated by the whole A/C system stuff since I have never had to deal with it before. I checked the A/C clutch and noticed it turns on and off, so it's not seized. I added a can of "A/C Pro" 134 and while it has helped a little bit...we still have days where it goes back and forth from hot to cold during a 20-30 minute drive. Is there anything else that I can easily check?? I would prefer to fix it myself but if need be I might take it to a shop if its over my comfort level. Thanks again in advance for all the help guys

Chuck

[ArmyGuy45]

Ok, so I picked up my "new to me" 99 XJ a few weeks ago. XJ is really clean and I have been luck to have no electrical or engine gremlins, so far. When I checked out the XJ at the dealership and on the test drive I made sure the A/C was on Max high for about 20 minutes and it stayed cool. The next two weeks the A/C stayed cool with no problems at all. Now I've noticed that some times it works and other times it will blow hot or just outside temperature air. I am somewhat mechanical compliant, but am a little intimidated by the whole A/C system stuff since I have never had to deal with it before. I checked the A/C clutch and noticed it turns on and off, so it's not seized. I added a can of "A/C Pro" 134 and while it has helped a little bit...we still have days where it goes back and forth from hot to cold during a 20-30 minute drive. Is there anything else that I can easily check?? I would prefer to fix it myself but if need be I might take it to a shop if its over my comfort level. Thanks again in advance for all the help guys

Chuck

Did they inject it with dye for leaks?

[XJ Wheeler]

Sounds like you have a leak and the system has a low pressure switch to cut it off if the freon is below a certain level.

Sent via messenger pigeon - i talk, he types.

[Mudderoy]

If it's going from cooling fine, to not cooling fine then back again and it's doing so without you adding any R134a, well, I don't think it would be a leak. Once the refrigerant level gets low pressure the cut off switch is going to keep the compressor from turning on. I guess the pressure could be changing depending on outside air temp, but I've never experienced that.

My guess would be a bad low pressure switch.

I let others with more A/C experience weigh in though.

[socalchuckster]

Where is the low pressure switch located?

[NW99XJ]

Where is the low pressure switch located?

http://0.tqn.com/d/autorepair/1/0/L/c/78600199.gif

[socalchuckster]

Any insight on how to change it? Is it just a plug and play thing or will I have to drain the 134 to have access to the plug?

[4.3LXJ]

It screws in and out. However the system will vent if you do it. Before trying that, take the plug off and bend a paper clip and shove it into the plug so there is a bypass. Then see if it still does it.

[Mudderoy]

It screws in and out. However the system will vent if you do it. Before trying that, take the plug off and bend a paper clip and shove it into the plug so there is a bypass. Then see if it still does it.

The plug end, the piece that has the wires attached to it.

[socalchuckster]

Awesome...thanks guys i'll see if that works

[Infidel Edition]

It continues to blow ~ but switches from cold to hot?
Or it stops blowing cold and...

Mine, the fan would simply cut out from time to time and it was the blower motor resister? Not sure if that would explain switching from hot to cold though...
http://www.oreillyauto.com/site/c/search/Blower+Motor+Resistor/02627/C0328.oap?keyword=blower+motor+resister&year=1999&make=Jeep&model=Cherokee&vi=1431776

[NW99XJ]

http://i519.photobucket.com/albums/u354/khinks01-02/HVAC/jpgXJACLOWPRESSSWJUMPERSERVIVINGPORT.jpg

[socalchuckster]

It continues to blow ~ but switches from cold to hot?
Or it stops blowing cold and...

Mine, the fan would simply cut out from time to time and it was the blower motor resister? Not sure if that would explain switching from hot to cold though...
http://www.oreillyauto.com/site/c/search/Blower+Motor+Resistor/02627/C0328.oap?keyword=blower+motor+resister&year=1999&make=Jeep&model=Cherokee&vi=1431776

No it still blows...it just goes from cold to kinda cool to warm. The blower isn't the issue.

[retiredff]

"still blows...it just goes from cold to kinda cool to warm. The blower isn't the issue."

Look to see if the clutch is still engaging, found the clutch on my '01 XJ stopped working when it got hot at higher RPMs.

[Mudderoy]

Awesome...thanks guys i'll see if that works

Oh and be careful with that low pressure switch bypass. You can trash the compressor if you leave it that way. The low pressure switch is there for good reason.