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Discussion Starter · #1 ·
Hey team,

I'm trying to diagnose few things happening with the A/C on my 2003 PT Cruiser (non-turbo automatic). I'm hoping there might be experts out there. :)

Here are the symptoms and what I have tried:

Symptoms
  • Air gets warm if I am at idle or not driving at a good speed (35 mph+)
  • The cooling fan does not turn on when I turn on the air conditioning
  • When the compressor clutch turns on it makes the engine bog down more than I've ever seen in another PT

Fixes/Tests I have tried:
  • Checked R-134a level and it is good/in the green
  • Replaced the low pressure switch on the accumulator
  • Checked all fuses and relays and swapped them to make sure

Once again when I am driving 35 mph+ the air does get cool and the A/C works ok - not as cold as I like or know that it should get but it works.

The fan only comes on when the engine warms up to full hot operating temperature - but never with the A/C.

Thanks for any help and advice!

Shane
 

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. . . .I'm trying to diagnose few things happening with the A/C on my 2003 PT Cruiser (non-turbo automatic). I'm hoping there might be experts out there.

Symptoms
  • Air gets warm if I am at idle or not driving at a good speed (35 mph+)
  • The cooling fan does not turn on when I turn on the air conditioning
  • When the compressor clutch turns on it makes the engine bog down more than I've ever seen in another PT . . . .
An indicator that you only get adequate cooling from the A/C system at higher travel speeds indicates that radiator fan is not operating properly at lower speeds and providing adequate air flow across the condenser to dissipate heat absorbed from the cabin. At highway speeds ram air effect provides adequate air flow across the condenser.

Engine bogging when compressor clutch engages is an indication of an over charged refrigerant system (high pressure) or a compressor with failing internal components.

There are 2 radiator fan relays in the PDC / power distribution center on the left side of the engine compartment. Check both of these relays for proper operation. The radiator fan is a 2 speed unit. You need to provide power to each circuit of the fan as a test to make sure it is functioning proerly.

Attached chart shows expected operation of the radiator cooling fan with respect to engine temperature, vehicle speed and A/C operation.

Rectangle Font Parallel Number Magenta


. . . .Fixes/Tests I have tried:
  • Checked R-134a level and it is good/in the green
  • Replaced the low pressure switch on the accumulator
  • Checked all fuses and relays and swapped them to make sure . . . .
Your reference to checking refrigerant level and it is in the GREEN indicates that you are using these quick, easy, DIY charging kits with a refrigerant canister, a gauge and connector for the low side port on the A/C system. These are very misleading. You need a professional set of A/C manifold gauges that monitor the pressures on the suction and discharge sides of the system along with knowledge as to how to interpret the readings. Only in that manner can you get an accurate diagnosis of system ills based upon these pressure readings. You could easily have the system overcharged with refrigerant and creating abnormally high suction and discharge pressures.
 

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It may have some air, instead of 100% refrigerant in the system. The A/C system is a closed system, if you had to add refrigerant, you have a leak. The leak must be found & fixed first & the cooling fan must work.

The compressor can compress 'air', but the high side pressure can skyrocket (especially if the condenser/radiator fan isn't working). Air won't absorb or release heat like refrigerant & can damage the system.

Air can contain moisture & elevated pressures can drag/overload the compressor. You are just measuring the low-side on a rudimentary scale.

The busy A/C service season is almost over with the return of cooler weather. Look for service specials & coupons.
 

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Agree with Imperial and Allan. Best to consult a licensed AC technician. It won't be inexpensive. The fan not coming on with the AC may be a simple fix (relay).
 

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Discussion Starter · #5 ·
Thank you @AllanC @ImperialCrown and @Doug D

Very helpful info and charts. I have done some research prior to posting leading me to some of the same conclusions but I am thankful to hear from some of you who are more experienced. I have swapped every A/C component on previous PTs but never had performance be quite right.

I do have a proper A/C charging/testing unit I got from Harbor Freight as well - but to be honest I haven't been able to successfully bring an A/C system back to its original state (cool enough) even using that. I suspect it is user error and I am doing something wrong...Perhaps going to a proper A/C specialist is best to actually charge the system for me.

I have tested both relays in the PDC (swapping them with known good - the horn relay for the High speed fan & a spare for the low speed). Perhaps the fan itself has failed and I need to test with a probe on the high and low speed pins of the connector. I will do that once I can jack it up.

I am suspicious that the Compressor may be failing though as well as it has had strange behavior for a number of years (my brother had this PT before me and described some issues - such as every now and then it would make a hiss and dispense a cloud out of the front around the A/C compressor area - almost like a turbo might dispense boost).

I will do a bit more testing and post results.

Thanks again folks.

Shane
 

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Sounds like the low speed fan for your radiator is just bad. Air needs to pass through the condenser to extract the heat otherwise the high side pressure goes way high and causes the engine to "lug". Replace the fan and all should be ok.
 

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Thank you @AllanC @ImperialCrown and @Doug D

Very helpful info and charts. I have done some research prior to posting leading me to some of the same conclusions but I am thankful to hear from some of you who are more experienced. I have swapped every A/C component on previous PTs but never had performance be quite right.

I do have a proper A/C charging/testing unit I got from Harbor Freight as well - but to be honest I haven't been able to successfully bring an A/C system back to its original state (cool enough) even using that. I suspect it is user error and I am doing something wrong...Perhaps going to a proper A/C specialist is best to actually charge the system for me.

I have tested both relays in the PDC (swapping them with known good - the horn relay for the High speed fan & a spare for the low speed). Perhaps the fan itself has failed and I need to test with a probe on the high and low speed pins of the connector. I will do that once I can jack it up.

I am suspicious that the Compressor may be failing though as well as it has had strange behavior for a number of years (my brother had this PT before me and described some issues - such as every now and then it would make a hiss and dispense a cloud out of the front around the A/C compressor area - almost like a turbo might dispense boost).

I will do a bit more testing and post results.

Thanks again folks.

Shane
In addition to a manifold gauge set, you should have a vacuum pump capable of pulling down to 30 inches of water. If you recharged the system without emptying it, you have a leak. If you recharged the system from empty without using a vacuum pump first, you have air and moisture in the system, which ruins it and hurts its cooling ability.
 

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Discussion Starter · #8 · (Edited)
Thanks @Airbornebarndoor1 and @Bob Lincoln

My brother has replaced the fan on this PT several times in the past for similar reasons or due to heating/cooling issues.

Could something be continually killing the low speed function of the fan?

While I can swap out the entire A/C system no problem I certainly don't feel like I have come to understand the voo-doo magic behind how it works and the mystery of getting it charged properly.

Shane
 

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The high-pressure safety blow-off valve is mounted on the compressor. It will blow excess refrigerant & oil in order to prevent damage or rupture.
Over-oiling the system can increase the load on the compressor and 'foam' in the lines will reduce cooling.

A fan motor may 'wear out' once, maybe twice during the life of the car. It is really only necessary at low speeds & stops. Traveling the highways, it shouldn't be needed. Bug-screens aren't recommended. The front of the condenser, cooler(s) & radiator must be kept clean.
OEM parts are suggested.
 

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. . . .I have tested both relays in the PDC (swapping them with known good - the horn relay for the High speed fan & a spare for the low speed). Perhaps the fan itself has failed and I need to test with a probe on the high and low speed pins of the connector. I will do that once I can jack it up.
. . . .
Attached is a wiring schematic for the radiator fan relays and fan motor. Run a jumper wire from battery positive to each power terminal (not ground) at the fan motor electrical connector. Ground the BK wire at the fan motor electrical connector. Fan motor should spin easily.

Rectangle Font Slope Parallel Pattern
 

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It is likely the fan. My mothers 2009 PT had the same symptoms as yours - and the low-speed fan was not turning on when the AC commanded it. Relay connections could be involved as well, so check for any corrosion as you run AllanC's jumpers to confirm this is just a fan problem. (By the way - Absolutely no engine temp problems were noticed even though the low speed fan failed).

A similar problem reoccured just days after installing an aftermarket fan from the local Auto Parts store zone. Whomever they got the replacement fan from used small gage wires for the high current connections! The connector melted internally due to the high-resistance and subsequent heat at the terminals, and the fan quit working again! I rewired it with the proper gage wires and it works fine to this day!

Good luck!
 

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Check the connector for the fan. These tend to get hot and can melt from time to time. Even the pins can become loose and if they recede just a little, they won't make a full connection. You really need to pay close attention to the connectors. This has been an issue with a lot of PT Cruisers.
 

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Check the connector for the fan. These tend to get hot and can melt from time to time. Even the pins can become loose and if they recede just a little, they won't make a full connection. You really need to pay close attention to the connectors. This has been an issue with a lot of PT Cruisers.
If connectors get hot, and have tin plating, they are probably subject to fretting corrosion, which causes oxidation and high contact resistance. This is a known issue in mobil and moderate to high-vibration environments. If so, apply a contact lubricant made for tin to the contacts, and it will mitigate the problem. Just replacing a connector with this condition will allow it to happen again.
 

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Discussion Starter · #15 ·
Hey folks - I was able to raise my PT up and start diagnosing the fan & A/C.

Here's what I found/did:

  1. Used a Power Probe to test the connections in the Power Distribution box for both the low and high speed fan relays as well as the A/C relay
    1. Following Relay tests were done with the ignition in the "run" position (car off) and the A/C switched on (blue dial on switch in dash 1 click to the left)
    2. Low speed relay connections check out ok and applying power (via Power Probe) to the "87" connector does activate the fan
    3. High speed relay (my main concern since the fan is not coming on with the A/C) - connections check out ok and applying power (via Power Probe) to the "87" pin does activate the fan
      1. Relay Pin 30 reads 12 volt + when I touch the probe
      2. Relay pin 86 reads 0 volt - when I touch the probe
      3. Relay pin 85 reads 0 volt - when I touch the probe
      4. Relay pin 87 reads 0 volt - when I touch the probe - fan turns on when I provide + power from the Power probe
    4. A/C relay (compressor clutch?) connections check out ok and applying power (via Power Probe) to the "87" connector does activate the compressor clutch
  2. I have a brand new fan I tested as well and it also does not turn on when I switch on the A/C. Same symptoms as the old fan so I don't think the fan is at fault.

I am wondering if my tests are indicating an issue with wiring somewhere between the switch and the Power Distribution center?
Or could there be an issue with the compressor itself that could cause the fan not to come on?

Thanks for all the advice.

Shane
 

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This is a good test setup, and indisputably, you have proven that the fan and the A/C clutch are good.

However, in order to understand the relay test, I need to know exactly where you placed both probes of the voltmeter to know if the relays are good.

We know that the relay contacts are: 86 is positive relay coil terminal (switched by ignition); 85 is the negative or ground relay coil terminal (switched by the computer); 30 is the positive load contact (always hot, always 12V); and 87 is the negative load contact, which runs to the device (fan or clutch).

With key on, engine off, relay open, you should have the following:
86 at 12V
85 at 12V
30 at 12V
87 at 0V.

If you close the relay and measure between contacts 86 and 85, you will have nearly 0V. If you measure 86 to a ground, you have 12V. If you measure 85 to a ground, you have 0V.
If you close the relay and measure between 30 and 87, you will have nearly 0V.

Do you hear or feel the relay click when energized? You can also close the relay and measure nearly zero ohms between 30 and 87 (don't do this test with the relay connected to the socket or the load!), and when open, you should get infinity (open circuit) between 30 and 87.
 

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A/C can be off for these tests.
Relay open is with it de-energized/contacts are open.
Relay closed is with it energized/contacts closed.
 

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Discussion Starter · #20 ·
Today I found these things out (in order):

@Bob Lincoln wrote:
With key on, engine off, relay open, you should have the following:

  • 86 at 12V - I am getting 0V
  • 85 at 12V - I am getting 0V
  • 30 at 12V - I am getting 12V
  • 87 at 0V - I am getting 0V

This prompted me to trace and test the wiring from the A/C fan switch in the dashboard. There is a solid Brown wire that should carry voltage to the Low A/C switch on the accumulator and I was getting 0V there as well. I am getting 0V at the A/C fan switch in the dashboard as well.

I then just decided to check all fuses and found that the fuse labeled "A/C" in the Power Distribution center was blown.
I replaced this but nothing changed.
I then found that Fuse 12 in the interior fuse panel was also blown.

I had to call it a night at this point but I discovered that any time I try to put a new fuse in slot 12 in the interior panel it blows.

I've attached photos of the two fuses I found blown. But it's only the Fuse 12 in the interior that keeps blowing.

Argh,
Automotive tire Wheel Tread Tire Rectangle

Green Circuit component Passive circuit component Automotive tire Computer hardware


Shane
 
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