Last post on Sep 02, 2013 at 6:33 PM
You are in the Chrysler PT Cruiser Maintenance & Repair
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Chrysler PT Cruiser, Heating / Cooling, Wagon
#74 of 249 Re: What finally worked for my A/C! [bthompson40207]
Jul 20, 2010 (3:00 pm)
Yes, being the novice that I am I paperclipped the LPS. So I'm supposed to put it on the clip with the wires attached to it?
#75 of 249 Re: What finally worked for my A/C! [kbraut832]
Jul 20, 2010 (6:24 pm)
I'm not trying to make you feel like a novice, but I will elaborate further for the other novices out there (like I was recently) .
The Low Pressure Switch (LPS) cycles the compressor based on the pressure in the accumulator (aluminum cannister that LPS is mounted atop). Pressure is a function of the temperature of the Freon liquid/gas cycle loop. This is why the compressor will not kick in at idle when the low-speed radiator fan is defective but it will kick in if the vehicle is at highway speed, or if the high speed fan can lower the condenser coil temp enough to trip a non-defective LPS. In other words, there must be enough air flow across the condenser coil to lower the pressure to the point that it will close the LPS and kick in the compressor.
By-passing the LPS via shorting out the connector contacts (the connector with the wires leading from it that plugs onto the top of the LPS) takes the switch and accumulator pressure out of the troubleshooting equation. The LPS switch contacts go to the computer module and the closed switch (such as when the contacts are shorted with a paper clip) signals the computer to tell the compressor to engage.
So, the paper clip test can not only by-pass the LPS switch and pressure as factors, it can also by-pass the low-speed radiator fan as an issue. In other words, if the LPS connector contacts are shorted, the computer will attempt to engage the compressor even though there may be low Freon, a bad LPS, and a decective low-speed radiator fan (assuming other components have been verified such as fuse, relay, and high-pressure cut-out switch).
Therefore, IF the LPS paper clip test causes the compressor to engage, then there are three things to check:
1. Low Freon
2. Defective LPS
3. Defective low-speed radiator fan
The cost to repair, respectively, (assuming DIY) is approximately:
In my case, I had both problems 2 AND 3.
As a caveat, if the paper clip tests does kick in the compressor, do not let the compressor stay engaged for more than the few seconds required to verify that it is running. Doing so with low Freon can damage the compressor; doing so with a defective low-speed radiator fan can cause excessive pressure to buld up in the system loop; doing so with a bad LPS can cause the coil to freeze up and produce other damage.
I am sure that there are professionals out there who can and will correct my explanations and/or logic, and I would welcome any additional information assistance or clarification, but, the above seems to be the mode of operation that eventualy led me to the correct troubleshooting that finally resulted in cold air - and without an outlay of hundreds of dollars (or more).
I hope this helps.
Jul 21, 2010 (7:37 am)
2005 PT Cruiser
I found this older post and was needing to know where the plug is to check
(You may have a plugged AC system drain. The evaporator and condenser remove moisture from the conditioned air and that water usually drains away while you drive. If the drain is plugged or damaged, the water collects inside the system.)
#77 of 249 Re: What finally worked for my A/C! [bthompson40207]
Jul 23, 2010 (2:18 pm)
You're not making me feel like a novice, I am a novice (at a/c work). I put the paperclip ends into the LPS connector, just made a loop with either end in the switch. Started the car, put the a/c on high and recirculate, just blew hot air.
Took the paperclip out, put the connector back on the LPS and started the car again with the air on high and recirculate, still no cold air, but it does continue to surge with the car in park and idle. The fan on the radiator does sound like it is on. We used to get cold air while driving but as of last Saturday nothing. Thanks for continuing to respond and help with this problem.
#78 of 249 Re: What finally worked for my A/C! [kbraut832]
Jul 24, 2010 (7:40 am)
The "surge" you describe would tend to make me believe that the compressor is being cycled. This could mean low Freon, but, that would be counter-intuitive to the fact that cycling requires a minimum amount of Freon.
That fact that you used to get cooling when traveling at high speed would make me believe that the low-speed radiator fan is not operating. Since you are no longer getting any cooling when traveling at high speed, this tends to also point to low Freon.
Use a flashlight to verify low-speed fan operation. The fan should come on as soon as the A/C is turned on.
You may have both a low-Freon issue and a bad low-speed radiator fan issue.
#79 of 249 Pt Cruiser air conditioning
Jul 25, 2010 (1:12 pm)
On a recent trip, the air conditioning would run great for about an hour, then it would quit, I would turn it off for about 30 minutes and then it would ran again. Temps were high 90's outside. I could hear the fan running but no air was coming thru the vents. This happened for the entire 6 hour trip. No problems on the way back, ran cold. Any ideas?? This is a 2001 that I just purchased about 3 months ago. Thanks..
#80 of 249 A/C PROBLEMS ON 08 CRUISER
Jul 26, 2010 (6:17 am)
I have the same thing going on with mine and can anyone help me out...here is what i have...the air is luke warm at idle and when the comp kicks on it makes the car idle real low...It gets a bit cooler when you are up to speed. I have also seen smoke coming from under the passenger side fender well a time or 2...I have did the paperclip thing and the comp cuts on when i jump it. the next deal os the cooling fan. It does not come on when I cut the air on...so I am asking should i buy a fan and put it on or try something else to make sure it isnt the relay or just low on freon....I also notice when the comp kicks on the small a/c line up on the firewall gets really cold fast...any help would be awesome....
#81 of 249 Re: A/C PROBLEMS ON 08 CRUISER [junkman1974]
Jul 26, 2010 (7:41 am)
It sure sounds like the low-speed fan. Swap the low- and high-speed relays located on the fan shroud to eliminate the relay from the equation. You should be able to use a flashlight to verify low-speed operation. If the low-speed does not kick in with engine running and and A/C switched on, the check out my previous post(s) on fan assembly replacement.
Jul 26, 2010 (11:09 am)
so i can just swap the plugs on the 2 relays that are on the fan shroud and if it is the low speed fan it should come on when i cut air on...Could the smoking be the fan motor?
Jul 26, 2010 (11:29 am)
If memory serves me, I believe that the relay connectors are snap-mounted to the shroud and the relays can be pulled up and off after releasing the snap catches. It is possible that fan motor coil burn-out could have caused smoke.