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Rear evaporator core, frozen fittings.

99Yukon on Wed July 22, 2009 7:24 PM User is offlineView users profile

Year: 1999
Make: GMC
Model: Yukon
Engine Size: 5.7L
Refrigerant Type: 134a
Country of Origin: United States

I flushed all the front lines for my AC system, but the lines to the rear evap are frozen, and I am afraid I will break the lines if I crack them open. dive been spraying them down with penetrating oil for a couple of days no luck. I was thinking if I left them on, what would be a good guesstimate for adding oil back to the system? I was flushing the system out because it was empty for a year. Any suggestion?

TRB on Wed July 22, 2009 11:18 PM User is offlineView users profile

Check out this thread. We have been able to save a few core but have lost a few also.

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NKENN on Thu July 23, 2009 12:21 AM User is offlineView users profile

I had a similar problem on the auxiliary (rear seat) evaporator on a Ford Excursion. I used a heat gun to heat the fitting as hot as I could get it, then, I sprayed it with some CRC Super Freeze penetrating oil that is supposed to freeze the joint and crack the rust (Corrosion in this case). I hoped to get a maximum effect by expanding the joint first and then contracting it rapidly with the CRC. It worked for me this one time. Good Luck!

Gerald K4NHN on Thu July 23, 2009 1:01 AM User is offlineView users profile

I did one connection like Tim said and it worked for me. I used a lot of Kroil, a tought joint to get apart, but it worked. I'll have to keep the one that NKENN said in mind, but I hope I'll never have to use either again.

Gerald K4NHN
Cayce, SC

Edited: Thu July 23, 2009 at 1:02 AM by Gerald K4NHN

torque395 on Thu July 23, 2009 1:34 AM User is offline

Most of the time you cant separate the lines from the rear evap core. When had to replace my rear AC stuff, i almost had to use new parts. I was lucky and found ONE junkyard that was able to get the lines and rear apart for me and not damage them. It really looked to me like it was a low mileage garage kept truck that was wrecked. If it hadn't been for that, i don't think it would have come apart either.

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1996 Chevy Suburban 2500 4x2 6.5L Turbo

GM Tech on Thu July 23, 2009 8:28 AM User is offline

In a/c work "frozen" usually means ice... I prefer the word "seized" - -

Welcome to the wonderful world of galvanic corrosion- dissimiliar metals that corrode together---

A lot of work to meerly flush-- units if there is a manifold- getting the nut, or bolt out is only half the battle, the rest is in separating the block fitting-- have had to drill them out befor and re-tap- just to save the evaporator-- gotta love corrosion...

I would not have flushed it. better off to leave it alone....

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

99Yukon on Thu July 23, 2009 9:53 AM User is offlineView users profile

Ok I came to terms that most likely the rear evaporator wont separate without something breaking. The problem is the front is already apart and flushed so at this point I am going to risk my compressor, and just add enough oil as if there wasnt rear ac.

TRB on Thu July 23, 2009 10:01 AM User is offlineView users profile

Quote
Originally posted by: GM Tech
I would not have flushed it. better off to leave it alone....

So what your plan then when a system is full of debris? I find the on rear systems a lot of debris is found in the rear lines. Leaving this behind is only asking for problems in my opinion.



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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

GM Tech on Thu July 23, 2009 10:28 AM User is offline

Inline filters, and suction screen in the compressor inlet- or TXV removal from the inside are all options- depends on failure mode- never debris for leaks- if pump is trashed- pull rear TXV- up inside the vehicle- no need to unhook underneath- cut a "door" in rear HVAC module- to access TXV per TSBs- saves time and effort as opposed to removing entire rear HVAC module...

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

TRB on Thu July 23, 2009 10:40 AM User is offlineView users profile

I'm not a fan of filter's and screens as a primary way to stop debris. All they do is clog up once the debris is caught and in many cases reduce oil return to the compressor. But agree sometimes is best to leave things alone. For me it just depends on the type of failure.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

99Yukon on Thu July 23, 2009 11:18 AM User is offlineView users profile

Well the system used to operate fine, the service fitting started leaking on the high side on top of the compressor. I am going to take everyones advice and not rush it, and try that drill bit tip to see if I can "unseize" the fitting. I am planning on a long trip this weekend NJ to ME, thats why I was rushing it.

TRB on Thu July 23, 2009 11:36 AM User is offlineView users profile

If all you had was a leaking compressor and zero debris. I would go with GM tech and not flush that section. Blow it out real well trying to remove as much oil as possible.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

99Yukon on Thu July 23, 2009 12:46 PM User is offlineView users profile

Ok even if I took that route, how much oil would I add back to the system? It calls for 11ozs.

TRB on Thu July 23, 2009 12:53 PM User is offlineView users profile

Flush everything else and blow out the lines real well, 11 ounces. This is of course with a new compressor and accumulator.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

cc61 on Mon July 27, 2009 8:03 AM User is offline

on the rear units on the 90s suburbans yukons etc.. we found a trick to remove the top cover from the box, after removing the cover(which is tricky but can be done in the vehicle) you can see the rear evap and txv you can drill a hole in the side of the box with a hole saw to get to one side of the txv for removal... after flushing and installition of new txv you can get a electrical knock out plug the same size as the hole and plug the box with silicone and the knock ou plug (usally the hole is high enough that you will not have condensation problems leaking etc) I know that is not the correct way but it works!!!

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