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PT Cruiser Air Conditioning Questions/Problems



  • dwjmd79dwjmd79 Posts: 2
    I am sure that the radiator fan does come on when the A/C button is pressed. So the fan is operating correctly. I am not sure how to properly do the paperclip test. I am also not even sure if I attempted the paper clip test on the correct sensor. For the paper clip test I inserted a paper clip into the sensor attached to the silver soda can looking container close to the engine firewall that has the low pressure freon pipe attached to it.

    I am also sure that the compressor does not come on at all at any point during my day or during driving or sitting idle. I did measure high pressure on the low end side when the car is completely cool. The pressure measurements were all taken when the ambient outside temp was 70 degrees F and the engine and car were cool, My friend thinks its a Low Pressure Switch or Low Pressure Sensor that engages when the low pressure side gets too high in order to shut off the compressor so it doesnt seize up or blow.

    I did have the radiator fan replaced last year and I had the radiator fan relays replaced as well. The radiator fan defect is a known issue with the PT cruisers that causes the A/C compressor to disengage and blow warmer and the car to overheat. After the radiator fan was replaced last year the A/C worked great until a few days ago.

    I will say that when the ambient temp was 75 or below and I ran the A/C at night it would blow so cold and the A/C coming from the vents would blow less hard yet extremely cold. When i turned the blower off and let the A/C "thaw" it would blow hard again and cold. It seemed to me like when the A/C was blowing cold at night it began to "freeze up" and the air coming out the vent would decrease in velocity the longer I let the A/C run. This happened at night when the outside temp was about 60-70 degrees. This was happening every so often for a few months. Do you think the "freeze-thaw" issue is the condensor or the blower that is causing the high pressure in my system and the compressor not to engage?

    Is there anything else that migh cause higher pressure readings on the low pressure side?

    And are there any other sensors that would cause the compressor to not engage?

    I do appreciate any feedback or ideas. You have no idea how much it helps. Looking forward to hearing from anyone soon. Thanks
  • mike573mike573 Posts: 1
    edited April 2011
    I have a 2002 pt with the folowing ac problem. Low speed fan does not come on when ac switch is turned on. compressor cycles on and off. Works great while in motion. Have been reading this forum to help trouble shoot. I jumped the LPS connector with no change in compressor cycling. I put power to fan motor and got it to work. Changed low speed fan relay and that also changed nothing. fan still will not activate when compressor and switch are turned on. Is there a high and low side to the motor or is that taken care of by the 2 relays. What should i check next?
  • gomermgomerm Posts: 1
    Ok I have a 2001 PT. A few months ago I had someone change the radiator. I don't know if that has anything to do with my problem or not. Anyway, As things started to warm up I tried to use the A/C and it didn't work. I hooked the A/C gauge to the car and it is reading 60 to 70 psi which is into the red on this gauge. I started the car and the compressor isn't kicking on. I pulled the low pressure switch off and shorted it with a piece of copper. The car immediately started surging at idle. I disconnected the jump wire and hooked the switch back up and it is still surging. I'm at a loss. Any ideas?
  • I am having the same problem. A/C works great when I am driving and blows warmer air and jerks when I stop/idle. Can you explain how I can look at the the low speed fan with the flaslight to detect a problem. I would like to check it out myself before a dealership. Thanks:)
  • Well all I can say is I replaced the the LPS switch and it worked for a day but thats it. You can start there, my next step is replacing fan, but before I spend a 100 on that I'm taking it to a dealership to see if the run a diagnostic on it as I am having other issues as well. I'm noticing some oil on valve cover and not sure where its coming from. Someone said I may need to replace the PVC valve have either of you heard of this one?
  • This is the first problem I have really had with my car. Hope you can get yours figured out. I hope it is the least expensive problem:)
    I just called PEP BOYS and am going tomorrow morning to have a diagnostic test run and to have them look at the fan to see. I tried the self test, but could not find a good angle to see the fan properly.
  • ginia740ginia740 Posts: 5
    Ok, this information is useful for me as I have an 08 that began having on and off AC issues at 49 k miles. Brought to dealer and they diagnosed a short and wanted me to shell out $950.00. The service separtment would not provide me with general information on the actual piece my car required but expected me to have the money to pay for it. Since last year (when the issues came about), my AC kicked on and off a total of 3 times. I have had no significant over heating issues with the car. It frightens me because the day before yesterday when I was driving the AC (after not working for 5 months) kicked on and blew dust in my face and scared me. I leave the nob on in the car because when I drive the cold air comes out of the vents and feels good in the AZ heat, but at a stay still nothing cames out only if there is a breeze outside. Do you think if replacing the parts you suggest will help my issue? It appears that there are similar issues with various years on this vehicle. :surprise:
  • Assuming that the freon is at full charge, perform the paperclip test first. Verify that the low speed fan is functional. You may only need the LPS or radiator fan/shroud assembly. These are two of the more common causes of failure. From the symptoms you describe, these are likely culprits.
  • ginia740ginia740 Posts: 5
    What is LPS? Is that a switch? I am wondering because if I can purchase the parts and if easy to install perhaps my boyfriend can install. He, also hates the heat; especially in June. Thanks for responding.

    Funny thing, today my AC did not work when I turned the car on. But, I started driving and began to turn on and off the nob for the AC and it turned on. :)
  • ginia740ginia740 Posts: 5
    additionally, can you explain the paper clip test? and to what areas in the car I perform this task. Thanks again....
  • ginia740ginia740 Posts: 5
    What is LPS? Is that a switch? I am wondering because if I can purchase the parts and if easy to install perhaps my boyfriend can install. He, also hates the heat; especially in June. Thanks for responding.

    Funny thing, today my AC did not work when I turned the car on. But, I started driving and began to turn on and off the nob for the AC and it turned on.
  • ginia740ginia740 Posts: 5
    So I looked at Auto zones website and for my car, there is a switch Duralast/A/C Heater Blower Control Switch Part Number: JA1472. Do you have any idea about this part? :shades:
  • The LPS is the Low Pressure Switch - a common cause of A/C failure. The LPS is what cycles the compressor on and off. It cost me $9.00 for a replacement at Auto Zone. Perform a search in this thread for my previous posts on how to troubleshoot and replace the LPS and the radiator fan/shroud assembly.
  • ollinmollinm Posts: 2
    I was having same problem. Last summer I took it to an a/c "expert" (his terminology) since I don't have guages etc.
    He charged me $70 to tell me that I need an $1100 compressor as mine was "weak." I decided not to do it. This spring I took it to another a/c shop. He worked on it for about an hour with his guages and code readers. He said he would have to put it on the rack and pull the fan from the bottom to see if it was the problem as he could find nothing else wrong and that I would have to bring it back later for that. He didn't charge me and seemed embarassed that he couldn't diagnose it.
    I took the upper radiator support off (6 bolts), leaned the radiator forward and took out the 4 fan shroud bolts, unplugged the wiring, and removed the fan from the top. I hooked a 12v battery to the ground and positive terminals of the wiring harness (3 wire plug). The fan would not run on low speed and was sluggish on high speed. I took the blade off the fan and oiled the fan motor bearings and put the blade back on. The fan worked from that point on both speeds. Apparently the motor is thermally protected and the dry bearing created enough heat to kick out the thermal switch causing the system to detect overheating and kick off the compressor at idle speed. I ordered a new fan that I will install as I feel that the problem will return due to wear in the fan motor bearing. The best price i found on the fan was $89 including shipping. Wish I would have taken this on from the beginning.
  • hbtmmmomhbtmmmom Posts: 3
    So, after 5 years, I have finally found out what has caused my 05 PT to shudder and have idling problems. Mechanic thinks it may be the Radiator Fan Module. Is this the same as Radiator Fan Assembly??? Also, I read the post about the paperclip trick, however, I am a un-mechanical woman. I just have to take it to mechanics and dealerships. So, with that in mind, how would a mechanic tell if the LPS is the prob or if it is the Fan Assembly? Finally, is the LPS something that typically gets replaced when the Fan Assembly/Module is replaced?

    Also, people keep posting on here that this A/C issue is a known issue with Chrysler. I called Chrysler yesterday and they knew nothing about it. They said they typed A/C into their database and nothing came up.

  • hbtmmmomhbtmmmom Posts: 3
    Dear dwjmd79:
    You had mentioned that this radiator fan issue is a known defect in PTs. I have a PT with this issue and I called Chrysler and they know nothing about it. They said if the part was "defective" that there would be a recall on it, but no recalls have been issued through NHTSA. Is this something that a mechanic told you or were you actually able to get someone at Chrysler to admit that there is really some defective parts on their precious PTs?
    Thank you
  • Just look at the sheer number of posts here regarding the radiator fan assembly (and this is just one forum). It is not unusual to find them failing after only two years. There is a reason that these fan assemblies are in stock and so readily available at so many automotive parts web sites.

    There is a big difference between a "Service Bulletin" and a "recall". A Service Bulletin for a defective part does not necessarily evolve into a recall unless these is a known safety issue. "No A/C" is not considered a safety issue.
  • A good mechanic will know how to perform the paperclip test. But, then on the other hand, many mechanics are not out to replace a $9.00 LPS. I and many others on this forum thread have been quoted anywhere from $600 to $1,200 for the"fan" repair. But, the LPS only affects the A/C and the defroster (the A/C compressor cycles in winter to remove moisture from the air stream blowing against the windshield). The only symptom you mentioned was the idle/shudder issue. Is your A/C also affected?

    I'm surprised that Chrysler did not find anything in their "database" regarding A/C. Especially since it has been reported hundreds of times on the internet.
  • hbtmmmomhbtmmmom Posts: 3
    Yes, the A/C is affected. That is how this finally got diagnosed for me. Thought it just needed refrigerant added, but the mechanic dug a little deeper when he discovered pressure issues and that the fan would shut off causing warm air to blow. Not sure if the defrost is also affected or not. I seem to remember a thud sound every time the defrost was turned on or off which is also something we hear when the A/C is turned on or off. And the car would shudder and almost die when stopped during A/C usage and I think defrost usage. I will have to check for sure on the defrost, though. Right now the focus is on A/C since it is hot. I will have to be in contact again with Chrysler. I think they are playing dumb. How can they not know of this? The dealership that will be servicing my car seemed to think this was a fairly common problem among PTs. He even fixed this issue on one last week. Turns out, that right after I bought my car, I took it into the dealership and told them about the shudder issue and that it felt like it was going to die when we were stopped and all, but they kept saying there was nothing wrong with it. It wouldn't shudder if the A/C was turned off during a stop light, though. Now we find out that the root of all this was most likely the fan issue. Infuriating since the car is no longer under warranty. But why should I have to pay for it now just because it wasn't diagnosed until now even though the problem existed 5 years ago when it was purchased?
  • All of your symptoms can be due to inter-related issues. A properly functioning LPS is required for the the low-speed radiator fan to engage when the A/C is switched on; a properly cycling low-speed fan is required for the compressor to work properly; and, the compression is what trips the LPS. Excessive compression (due to a non-functioning low-speed radiator fan) can cause the engine to "shudder" because idle speed is insufficient to overcome the pressure in the A/C system.

    As proven in these and other forum posts, problems with the LPS and the low-speed radiator fan (and ultimately the A/C) are common in the PT Cruiser. They are also not uncommon in other Chrysler vehicles.
  • terry1703terry1703 Posts: 1
    I had a pressure test done on my 2002 PT Cruiser AC and I was told that I had a leak at the top of the Condensor. Yet when I search on line I keep getting results for the compressor. Are these one and the same thing and just go by different names depending on the shop doing the work?
  • No, the compressor and condenser are not the same thing. The compressor is the mechanical piston-driving device powered by a belt that compresses the freon gas. The high pressure vapor output of the compressor is fed into the condenser that is located adjacent to the radiator. The low speed radiator fan supplies constant air flow across the condensing coils which converts the freon vapor into a liquid form. An expansion valve after the condenser coil allows the liquid freon to form into a low pressure gas that flows into the evaporator coil inside the car. The A/C fan blows air across the evaporator coil and through the duct work into the passenger compartment. The low-pressure freon gas is sucked from the evaporator coil and into the compressor as the cycle repeats itself.

    So, to put it in short form, your leak is in a coil of tubing in the exterior of the vehicle parallel with the radiator.
  • Way to go! This is exactly the kind of self-service that everyone should try for themselves before shelling out hundreds of dollars for what are essentailly low-cost solutions. While I acknowledge that not every repair can be simple or cheap, it seems that the majority are.
  • I have. a 2005..same air problems.. Warm are when stopped at a light, noise, etc..first place said air needed charging..I paid but did no good. Next place charged over $200 said it was a leak..worked a month then quit completely! Next, one of the tubes was blocked. $180 to fix. When replacing, found medal shavings. Apparently, compressor slowly falling apart causing blockage..and problems. Now, $700 !! Who knows! It sure is miserable with no air though! It's been over 100 every day!
  • Spend the less-than-20-dollars needed for the LPS and then take five minutes to replace it before you spend any more big bucks. If it works then celebrate, if it does not, then you will have spent a few dollars to eliminate one of the more common causes of PT Cruiser A/C failure as the source of your issues.
  • deb904deb904 Posts: 1
    I would like to know where the low speed fan relay module is located on my 2008 pt cruiser. does anyone know?
  • I replaced the LPS switch, put sealant and also tried detecting a leak in my AC system. Never fails after adding refrigerant it works for two days and goes back to not working. The compressor and fan both kick on once there is refrigerant in the system, so i'm thinking neither of them need replaced. They want $120 at the local dealership to run a diagnostic and leak test. Which to me is ridiculous. Any suggestion on what may be my problem.
  • And "good mechanic" does not include the guy at the Chrysler dealership who told my husband (after we refused to pay the $900 to fix this problem which is just more of an annoyance to me) to "get it fixed or the engine could stop running". LOL LOL LOL What an idiot.

    My husband's best friend knows all about cars so we're sending him the link to this forum page to see how he can help.

    I do have a question (and apologies if I don't see the answer here): what the heck is the paperclip test?

    Cindy :blush:
  • The paperclip test is used to eliminate the LPS as the source of system failure. Go back and find the detailed description of how to perform this simple test in posts from last year. I believe I posted them around May or June of 2010.
  • For those of you asking about the paperclip test. Go back and read my posts starting with #60 in this forum. There are detailed descriptions of how to perform the test (very simple) and I have also posted other troubleshooting tips. There is also a detailed description of how to replace the LPS and how to replace the radiator fan assembly.
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