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2002 VW Beetle intermittent cooling


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comnavguy
User

Jul 23, 2013, 6:24 AM

Post #1 of 16 (3970 views)
2002 VW Beetle intermittent cooling Sign In

2002 Beetle with 2.0L engine and 127,000 miles just started blowing cold intermittently. I suspect one of the pressure switches but I can not locate the low line pressure switch.

Can you give me the location of the low pressure switch and the wiring diagram of the low and high switches? I've traced the return line from the firewall back to the compressor and can not see a pressure switch anywhere on that line. Is it possible it's built into the compressor?


Hammer Time
Ultimate Carjunky / Moderator
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Jul 23, 2013, 7:13 AM

Post #2 of 16 (3959 views)
Re: 2002 VW Beetle intermittent cooling Sign In

That's because it doesn't have one.




















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comnavguy
User

Jul 23, 2013, 11:49 PM

Post #3 of 16 (3927 views)
Re: 2002 VW Beetle intermittent cooling Sign In

Thanks for the info and schematics. I'll go and put my pea brain to work to see if I can solve the problem.

I evacuated the system and it held for over an hour. I tried recharging. I got about 75 PSI on high and low side but the clutch would not engage. I jumpered the clutch and it engaged. The pressure on the high gauge started climbing but as soon as I disconnected the jumper, the clutch disengaged. The fuse is good. I have not yet gone under the dash to check the relay(s).

Am I right that the problem is most likely the high pressure switch or the relay?

Can you tell me the approximate resistance between pins 1, 2 and 3 on the high pressure switch? I measured 4K between 1,2; 1,3; and 2,3 with the switch off the system.


Hammer Time
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Jul 24, 2013, 2:56 AM

Post #4 of 16 (3918 views)
Re: 2002 VW Beetle intermittent cooling Sign In

These are not fun cars to work on and you may regret getting involved.. That switch is only one of 20 or more things that can cause the compressor to cut out up to and including the PCM. That switch will cut out for both high and low pressures. Resistance is not the way to test it. You have to look for continuity in the circuit.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



comnavguy
User

Jul 24, 2013, 6:51 AM

Post #5 of 16 (3911 views)
Re: 2002 VW Beetle intermittent cooling Sign In

You are more than right about the absence of fun. The fuse legends/icons are a puzzle by themselves, and why any designer would hide the relay panel is beyond reason. I'm going to see if I can swap a couple of relays and if that doesn't work, I'll spring $24 for the high pressure switch; but I hate just throwing parts at a problem. And giving up is not in my nature.


Hammer Time
Ultimate Carjunky / Moderator
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Jul 24, 2013, 7:42 AM

Post #6 of 16 (3907 views)
Re: 2002 VW Beetle intermittent cooling Sign In

Yeah, I wouldn't recommend the dartboard method.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



comnavguy
User

Jul 26, 2013, 10:08 AM

Post #7 of 16 (3876 views)
Re: 2002 VW Beetle intermittent cooling Sign In

We did replace the high pressure switch. Nothing.

So, do you know which relay under the dash is the AC relay?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 26, 2013, 12:35 PM

Post #8 of 16 (3872 views)
Re: 2002 VW Beetle intermittent cooling Sign In

I told you that you'd be sorry.


Compressor Clutch Engagement

On Golf/Jetta and new Beetles, current to the A/C Compressor Clutch -N25- is supplied by the Coolant Fan Control Module -J293-. This module is switched by the A/C switch -E35- on the manual A/C systems. On Passat models, the current to the A/C compressor clutch is supplied by the A/C Control Module -J314-. Inputs from pressure switches, temperature sensors and other control modules are processed by Coolant Fan Control Module -J293- to determine the compressor on/off state.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



comnavguy
User

Jul 28, 2013, 2:15 AM

Post #9 of 16 (3855 views)
Re: 2002 VW Beetle intermittent cooling Sign In

Sorry is not even half the story. The cost and frustration is beyond imagination.

I really appreciate your giving me this latest information. It is good that we have the manual system. I just found that the ambient temp sensor is bad. Ambient is stuck at 69 whether I heat it with a heat gun or cool it with component cooler spray.

I'll replace that sensor Monday. If you see blood coming out my eyes Monday evening...


Hammer Time
Ultimate Carjunky / Moderator
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Jul 28, 2013, 4:36 AM

Post #10 of 16 (3854 views)
Re: 2002 VW Beetle intermittent cooling Sign In

I seriously doubt that is preventing the compressor from engaging.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Jul 28, 2013, 10:30 AM

Post #11 of 16 (3851 views)
Re: 2002 VW Beetle intermittent cooling Sign In

I don't see any diagnostic test results, just a bunch of guessing and changing parts.





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comnavguy
User

Jul 31, 2013, 12:47 PM

Post #12 of 16 (3828 views)
Re: 2002 VW Beetle intermittent cooling Sign In

We are not just guessing and throwing parts at the problem. As best as we can without a shop manual, we are tracing wires, testing for shorts or opens or corroded grounds or the 30 AMP fuse on the top of the battery that seems to be intermittent (*) on MANY VWs and Audis. As a DIYer I don't think I'm too far wrong when I say this Rube Goldberg AC design on those cars is a bad joke.

Not that it's any consolation, but when I go to two different AC specialty shops and they roll their eyes and say, "Dealer" when I tell them the year, make and model of the car, I feel less inept.

When HT (a superman in my estimation) tells me that I'll be sorry I took on this job, I feel less inept.

But all that being said, all we've done so far it to eliminate two possible components causing this failure. I'm still looking for help and suggestions as to the other specific parts we could check/diagnose to get the AC working.

How about you? Do you know of any relays, specifically under the dash that are in the AC system? Say for instance relay 175 or any others by the steering column? Do you have any suggestion(s) other than "dealer"? I need help.

* Yes, I've worked on some of the most cutting edge electronics on the B47, B52, KC97G an KC135 and AF planes and I've never seen an intermittent fuse. This one is not really intermittent, but the fuse holder blades get corroded and don't make good contact causing AC to work intermittently. So just looking at the fuse in the normal way shows that it's good)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 31, 2013, 1:47 PM

Post #13 of 16 (3825 views)
Re: 2002 VW Beetle intermittent cooling Sign In

As I already posted, the compressor doesn't use a relay. It's operated by the cooling fan control module.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



comnavguy
User

Sep 17, 2013, 10:50 PM

Post #14 of 16 (3705 views)
Re: 2002 VW Beetle intermittent cooling Sign In

I'm not being obstinate just for the exercise. I was told by several "experts" that there was another relay under the dash. There IS a relay under the dash but it operates the glove box on a Studebaker next door.

The car was taken to a VW dealer to specifically diagnose the A/C. Cost $122, and they came back with a laundry list of things that "needed" to be done BEFORE they could diagnose the A/C - including replacing the Alternator wiring harness and the fuse box. After that needless work was done, they said the high pressure switch was bad.

I replaced that switch twice. Did I get 2 switches bad out of the box???

The dealer wanted $465 to replace that switch and recharge the system. The customer declined, and I don't blame her.

I disassembled one of the "bad" switches, and it's easy to see how one could get two bad out of the box. Rube Goldberg would give VW the Decade's top award. What a lousy over designed AC mess.

We replaced the switch for the 3rd time, and the system is working but still goes warm occasionally.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 18, 2013, 2:41 AM

Post #15 of 16 (3702 views)
Re: 2002 VW Beetle intermittent cooling Sign In

See, now you also will run the next time you see a VW bug with no AC.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



comnavguy
User

Sep 18, 2013, 9:54 AM

Post #16 of 16 (3695 views)
Re: 2002 VW Beetle intermittent cooling Sign In

I'm way past the age of running - three heart stents, anemia and other health issues, so walking briskly is an accomplishment, but I'll get on my scooter and burn rubber leaving the scene. It won't just be from Beetles either.

It was a learning experience, to say the least.

However, when I hit the Powerball tonight, I'll still buy an Audi A8 and maybe even an R8. $400 K is pocket change when you just won $200 million?

Now back to reality...






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