1990 K1500 a/c repair

[idlook2]

I bought a 1990 K1500 with a frozen a/c compressor. The previous owner routed a shorter belt around the a/c compressor and it appear to have been this way for quite some time as the a/c pulley has developed some rust on it. The compressor looks original to the truck and I can barely turn it it by hand.

I have not done a lot of a/c work in the past (replaced a compressor once but it was on a newer vehicle that already had r134a). What I’m trying to do is figure out what parts I need to buy to get the a/c running again and converted to r134a. So far:

Compressor: GM brand, 1520185

Drier/accumulator: GM brand, 151676

Orifice tube: There appears to be several variations of this part, which one do I need?

Lines: Do I need new a/c lines?

Condenser: Do I need a new condenser?


Oil, Flush, adapters, o-rings?

Hoping to find someone that has done this before to help me get a parts list together.

 

[Steven Petersen]

Maybe it’s already been converted? Does it have R12 screw on fittings or R134 quick coupler type? First thing I would do is pull a vacuum on it and see if it holds. If it holds, do a flush then replace compressor, dryer and orifice tube. Pull another vacuum. If it holds, charge with 134.
On the 88 I bought last year, AC was functioning but low on Freon due to a leaky compressor. I put a new GM compressor, orifice tube and dryer. Recharged with R12 and it works great. Just beware that when those systems are converted to 134, they don’t cool quite as well. It’s adequate, but not the same.

 

[man-a-fre]

I would start with breaking the fitting loose for the new orfice tube, the fittings are usually seized on both ends of that aluminum tube which takes the threads out then you need to add more parts to your list. Don't take the threads off the evaporator or your in for a tough job replacing it. Dorman makes a ac line splice 800-641 that may come in handy if there seized.Crack the reciever drier fitting loose too to see if it is seized,the threads like to seize on it too . If it doesnt move dont force it you don want the evaporator threads ruined or your screwed.

 

[kenh]

I just did this on my truck early summer on 2020. Advance auto has a "kit" with everything you need to convert to 134A EXCEPT the correct 134A charge fittings. Those are cheap enough to buy. The kit has the compressor, drier/accumulator, o-rings, orifice tube and oil. It is less money and there is no core charge on the old compressor compared to buying the individual parts. It is a "Factory Air" brand.

https://shop.advanceautoparts.com/p...95nk/11893507-P?searchTerm=a/c compressor kit

Ken

 

[Steven Petersen]

I’m not sure what year they switched to 134. My dad’s 92 was R12. If the 93, 94 or 95 was 134, I’d buy the compressor from that application. Compressors designed for R12 never seem to work as well converted as those designed for R134a.

 

[Frank Enstein]

An AC guy in Florida told me when converting mid 80's to mid 90's GM vehicles to R134a to use the blue Ford orifice tube. I have done a half dozen and they all work well.

+1 on the flush and caution on the fittings. I always put some refrigerant oil (whatever kind the compressor wants) on the fittings when I assemble them.

I have found that the info on the amount of oil for the system is often vague.
I recommend contacting the compressor manufacturer for the amount and type of oil and how they want it put in (pour it all in the compressor, half in the compressor and half in the receiver-dryer/accumulator & etc.).

Any time the system is opened replace the accumulator and orifice tube and you can't go wrong.

 

[man-a-fre]

Don't put pag oil on fittings and orings use mineral oil it doesnt draw moisture like pag. Using pag oil on threads will cause thread corrosion and seize them.Pag oil should be used in the system just not at fittings.

 

[Steven Petersen]

An AC guy in Florida told me when converting mid 80's to mid 90's GM vehicles to R134a to use the blue Ford orifice tube. I have done a half dozen and they all work well.

+1 on the flush and caution on the fittings. I always put some refrigerant oil (whatever kind the compressor wants) on the fittings when I assemble them.

I have found that the info on the amount of oil for the system is often vague.
I recommend contacting the compressor manufacturer for the amount and type of oil and how they want it put in (pour it all in the compressor, half in the compressor and half in the receiver-dryer/accumulator & etc.).

Any time the system is opened replace the accumulator and orifice tube and you can't go wrong.

The GM service manual is very specific on how much oil to add when a certain component is changed. I believe he will need to flush the whole system of the mineral oil.

 

[Frank Enstein]

Don't put pag oil on fittings and orings use mineral oil it doesnt draw moisture like pag. Using pag oil on threads will cause thread corrosion and seize them.Pag oil should be used in the system just not at fittings.

Oh NOW you tell me!

 

[Steven Petersen]

Y

An AC guy in Florida told me when converting mid 80's to mid 90's GM vehicles to R134a to use the blue Ford orifice tube. I have done a half dozen and they all work well.

+1 on the flush and caution on the fittings. I always put some refrigerant oil (whatever kind the compressor wants) on the fittings when I assemble them.

I have found that the info on the amount of oil for the system is often vague.
I recommend contacting the compressor manufacturer for the amount and type of oil and how they want it put in (pour it all in the compressor, half in the compressor and half in the receiver-dryer/accumulator & etc.).

Any time the system is opened replace the accumulator and orifice tube and you can't go wrong.

Your comment about using the Ford orifice tube got me thinking. Would R12 and R134a use a different tube? I know R134 molecules are smaller that’s why the systems are more prone to leaks than R12, plus they run at higher pressure.