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Air Conditioner Performance Tests

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Old 02 Jun 2012, 08:49 pm
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Location: Mooresville, NC
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Default Air Conditioner Performance Tests

As some of you know, for years now I've been collecting all the data I can find related to the PT Cruiser. Recently I had an issue (or so I thought) with my PT's air conditioner, so I had to look up how to troubleshoot, test, repair, recharge, etc., the AC. Now, once again, I'm back with a simple 7-step register for AC Performance Tests. I hope that these are helpful to you all, they certainly were for me.

Now basically what I've done is gone through MANY sites relating to air conditioner servicing plus the entire AC service section of the OEM Service Manuals, both 00-05 and 06 and up. What I've done is compile a simple method for your use that will help you identify if you have a real issue with your AC or if it's something simple to fix.

Later on I'll be adding to the forums different sections with step-by-step procedures on the following AC subjects: PT Cruiser AC System Basics, How to Recharge Your AC System, and How to Find and Repair AC Leaks. My goal is to have the Admin and/or Mod add a section specific to AC & Heat, where I can create threads for AC Systems Maintenance, Troubleshooting & Repairs.


PT Cruiser AC Performance Test

SAFETY NOTE: Anytime you are working under the hood of your car, especially when working on your AC System, make darned certain that you are wearing eye protection! Touching and/or manipulating your AC system can open a small leak and cause a large leak, and if you're sprayed in the face, the AC coolant can literally freeze your eye(s) and cause permanent damage! No Joke, IF YOU ARE GOING TO WORK ON YOUR AC SYSTEM, WEAR SAFETY GLASSES! I also suggest gloves of some sort, personally I use those inexpensive hospital type gloves.

Step 1 - Check vent temp: Get you an AC thermometer (any thermometer will work, however the ones designed for AC Work are best) and set it into one of your center air vents (center console of the PT, vents to either side of the clock). Note the temperature indicated as your 'ambient' temp.

A good example of an automotive AC thermometer - note that it has a long stem to allow it to go down the AC duct for a good reading. The red piece is a cover for it. Sure, there are plenty of different types, including digital, but personally I prefer a good, analog thermometer for this purpose. I noticed that most of these are around $20 on ebay, however Advance Auto has them for like $5!

Step 2 - Again, make sure that you use one of the center vents to test the vent temp. Start your engine. Turn on your AC, make sure it's set at it's lowest temperature, make sure that you have the system fan on Low, and make sure you are in 'fresh air' mode (make sure the recirc button is off!).

Step 3 - Press on the gas pedal and raise your RPM's to approximately 2000 RPMs. Monitor the temperature gauge for a few moments and it should drop approximately 30 degrees if the AC system is working properly. Mind you, the ambient temperature and humidity has a direct affect on your car's AC cooling capabilities! Higher humidity/temp, the harder the system has to work to cool. If it's really hot and/or humid, your AC system may only drop 20-25 degrees, rather than the target 30. NOTE that the OEM Service Manual has a section that shows you charts that indicate, based on ambient temperature, how much your AC system should cool down.

From 2000-2010 OEM Service Manuals (all the same):

Step 4 - If your temperature drops approximately the target amount, then your system is working fine. If it doesn't, say it drops only 10 degrees, then you need to do more work to see if your system is functioning properly.

Step 5 - Open the hood and look at your AC compressor - the compressor system should kick on, starting the flow of coolant through the system. If it's not kicking on at all, then you have other problems to troubleshoot. If the AC compressor is kicking on, then go to the next step.

Look down by the passenger side fender well, and you'll see the AC compressor towards the bottom. Has a belt around it. Inside that pulley with the belt on it is the compressor clutch, shown here:

Step 6 - When the clutch on your AC compressor engages, then your cooling fan on the radiator should kick on. If it is turning on, then go to the next step.

Step 7 - You need to verify that your condenser is not clogged, meaning that it doesn't have trash, bugs, leaves and such blocking it. Items like this, especially plastic bags, will cause your condenser to reduce in efficiency. I suggest using a lightly powered jet washer to clean the condenser assembly out at least a couple of times a year. No debris in front of the condenser then you system should be working fine.

Note that your AC Condenser is IN FRONT of your Radiator! If the condenser is blocked, or lots of the cooling fins damaged, you can block the airflow through to your radiator and cause your engine to overheat! There are Radiator and Condenser combs out there that you can get to correct the cooling fins, and that takes a lot of effort and work. Personally, I use my jet washer and once per year I jet wash the front end after removing my grill. Here's a picture on the '06 PT GT and the location of the condenser:

Now if you have gone through all 7 steps and you don't find any issues other than the system is not performing as it should, then you need to go into the full AC system diagnostics. You may have low system coolant, low system pressure, coolant leaks, moisture in your system, etc. Please see the OEM service manual for the complete AC System Diagnosis - it gives you very detailed troubleshooting steps that can really help you determine your AC Systems issues in little time.

I will be back later on to load up further troubleshooting steps, but for now this is the easiest part. Hopefully, you can work through this and find your problems, if not then you might want to look for newer sections of this category.

Last edited by Chromenut; 02 Jun 2012 at 08:54 pm.
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  #2 (permalink)  
Old 02 Jun 2012, 09:33 pm
Obsessed Cruiser
Join Date: Sep 2001
Posts: 27,758
Default Re: Air Conditioner Performance Tests

Great Job Chromenut. Added a link to this thread in the HOW TO section.
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Old 02 Jun 2012, 10:35 pm
Obsessed Cruiser
Join Date: Nov 2007
Location: Mooresville, NC
Posts: 5,324
Default Re: Air Conditioner Performance Tests

Originally Posted by CREWZIN View Post
Great Job Chromenut. Added a link to this thread in the HOW TO section.
Got more coming! Hey, how are you and the wife doing? Please let me know if you need ANY help!!! How's that iPad? I'm getting ready to get one for my daughter, while she's 'legally' blind and deaf, she can see about 3 feet away and loves playing on the iPad. Her speach therapist just recently moved to DC, so now I have to get her an iPad and put the therapist's apps on it. She really loves that thing. Just wish she could talk!!!
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Old 17 Jun 2013, 03:07 pm
Fresh Cruiser
Join Date: Jul 2012
Posts: 7
Default Re: Air Conditioner Performance Tests

Don't know if anyone can shed any light on my AC..paid over 600 last year to have the compressor replaced and the fan..working fine since. Now over the last few days my thermometer is getting 'stuck'..clearly not showing the correct external temperature and coincidentally also noticed that AC is not working!! I've noticed in the past that sometimes thermometer gets jammed and then after engine is turned off for a bit and then turned back on it resets the display temperature to ' --' and then eventually gets back online and shows correct temperature. Was wondering if this is a similar electrical type fault with the AC this time as can't see that anything major is wrong after the work we've had done on it just 8 months ago..Anybody got any ideas on what could cause this or how to fix it?? I can't live without AC!!!
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