Automotive Air Conditioning Information Forum (Archives)

wm8728 on Thu April 03, 2014 2:21 PM

Year: 1987
Make: Chevy
Model: RV
Engine Size: 7.4L
Refrigerant Type: R12
Ambient Temp: 80F
Pressure Low: unkwn
Pressure High: unkwn
Country of Origin: United States

My best friend bought this well-cared for Pace Arrow RV with 56k original miles. The rear AC is your typical 120VAC R22-style unit - it runs fine. The front AC has a known bad compressor, so that is what I have to work with. I plan to flush everything but the condensor... I feel more comfortable with a known clean unit in case the worst has happened (Black Death). I don't know of any reputable AC shops in the Little Rock area that have HECAT flushing equipment or equivalent... if anyone else does, *please* let me know; else....

Does anyone have any experience with the difficulty in removing/replacing the condensor on this beast? And I assume it uses an O-tube. I really hope it uses a TXV. If anyone knows the answer to any of these, please holler!

This weekend will be the first time I get to lay my hands on it. If I'm lucky, there will still be a partial charge in the system. If I'm *really* lucky, the o-tube (if present) will be clean (lol... fat chance) and there wont be trash in the condensor or anywhere else.

Cheers!
Biker Bil

Dougflas on Thu April 03, 2014 4:42 PM

If you want to know if the system uses a TXV, look for a drier in the line after the condenser. If the suction line has a tank in it, then you have an orfice tube.

mk378 on Fri April 04, 2014 8:58 AM

You may find it is just the truck's GM stock dash air system. In that case of course work on it like it was a regular truck.

Aftermarket setups are almost always TXV. An OT setup trades more upfront engineering effort for lower unit cost, which is only practical on large production runs.

HECAT on Fri April 04, 2014 9:47 AM

I wish I could help you with a user reference, but as the manufacturer that sells thru distribution; I have little data on end users locations. A 1987 R-12 GM system will most probably be an o-tube system with a tube and fin style condenser. The location of the filter/dryer/accumulator will determine if OT or TXV. Look at the design of the condenser; the tube and fin is going to be a lot easier to effectively clean. Although old contaminated and heat cycled oils can be black; true "black death" which clogged condensers was a specific Ford FS10 issue.

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wm8728 on Fri April 04, 2014 11:31 AM

I looked at the replacement condensor on the host site and it does indeed appear to be a "tube and fin" style, which I feel a little more confident in cleaning myself.

I just don't want a repeat of a failure I had with a 94 Toyota pickup. It had the parallel flow conedensor and I took it to a known pro in the Dallas area to have it professionally flushed. After I personally cleaned all the rest of the components and replaced the TXV, it cooled great.. for about a year. Then it suffered another compressor failure. The pro flusher didn't exactly sound confident that their flushing would be adequate. But this was back in the days when most believed that the PFC's were non-flushable. The HECAT Technical bulletin has removed all notions about that.

I will send an update after this weekend to confirm that this wil simply be a garden-variety FOT system, with the attendant caveats. WIth the age, I will be on the lookout for replacing old rubber tubing.

One final item: from what I have read, this system will need 48oz of R12 and 8oz of mineral oil + 2oz for the new accumulator. Is it easy to over-oil these FOT-style systems?

Thanks to one and all, and keep on chillin'!
Biker Bil