Question about R4 "Pancake" AC compressors

[CheemsK1500]

My 84 K1500 has factory AC, but the old R4 compressor is pretty much dead and all the old R12 has leaked out. After some reading, it appears that there was an R134a version of the R4 built for GMT400 that were made after the R12 ban. Is one of these newer style compressors just a bolt on affair, or are there other changes that need to be made. I have all the R12 to R134a manifold guages and adapters to charge the truck with already. I just want to make sure everything fits before I fully commit.

 

[Vbb199]

Following myself, because I have the original r12 compressor on my 89 burb, and it's gonna get replaced with a junkyard unit, I had already done the conversion and even put a gmt400 low pressure switch on my system

The compressor eventually couldnt keep up anymore and just kept leaking and hitting the high pressure limit.

I've got my eye on a 80's model g30 with a 6.2 and AC for its compressor. But this sounds intriguing, as r134a operates at a higher pressure than r12, so it's gonna work the compressor also.

 

[crpntr78]

The only thing I know about them is maybe a reverse rotation be cause of either being mounted on the opposite side of the engine or perhaps from the serpentine belt system.

 

[85K304SPD]

You will need a new drier/filter and an adapter kit for the quick connects. Probably a new orifice tube. I have this set up on my '85, but it is with the reverse rotation serpentine belt set up. Make sure you get the compressor that fits your v-belt set up, as well as the same inlet and outlet sizes as your original. Make sure that the old system isnt full of trash from an old exploded compressor. Maybe there is more, but that is what I can think of.
Hopefully the hoses dont leak.

 

[Backfoot100]

Thread 'Retrofit AC upgrade results' https://www.gmsquarebody.com/threads/retrofit-ac-upgrade-results.25503/

Hopefully that link works. Don't F**k with the R4. Do it right.

 

[Doppleganger]

^ What Backfoot said. The brackets I am forced to use were originally for an R4 unit. I'm going to use the Sanden retrofit (couple of brackets) and go that route.

R4's work great on the end of a chain at keeping your boat from drifting - otherwise, I wouldn't bother with it.

 

[CheemsK1500]

I want to try a Sanden unit, but I also don't want to go through the headache of bracket, belts, and refrigerant lines, I don't have to. If it isn't too much of a headache, I'll try it.

 

[CheemsK1500]

After a little bit of digging, it looks like a R4 to Sanden 508 conversion on a small block is pretty straight forward, since there are already conversion brackets available.

What do ya'll reccomended for refrigerant line? Will I still be able to use an OEM style dryer can?

 

[fast 99]

When spending that much money and labor the system should be flushed. R12 oil and some 134A oils aren't compatible. If the R12 oil is left in the system, it usually won't cause an issue but being as the system is open it isn't much more work and the system will work better. The AC hoses are probably old replacing them now would be a good idea, new hoses are barrier. Be sure and replace ALL the O-rings. Find the AC label, charge to 80% of the R12 capacity. Do not overcharge.

Buy some extra 134A. My state has already halted counter sales for DIYers
Nationwide, 134A has tripled in price since last year. There are rumbles about stopping production.

 

[CheemsK1500]

When spending that much money and labor the system should be flushed. R12 oil and some 134A oils aren't compatible. If the R12 oil is left in the system, it usually won't cause an issue but being as the system is open it isn't much more work and the system will work better. The AC hoses are probably old replacing them now would be a good idea, new hoses are barrier. Be sure and replace ALL the O-rings. Find the AC label, charge to 80% of the R12 capacity. Do not overcharge.

Buy some extra 134A. My state has already halted counter sales for DIYers
Nationwide, 134A has tripled in price since last year. There are rumbles about stopping production.

I am honestly starting to think they just declare the previous generation of refrigerant deadly to get it regulated out of existence and force the industry to invest in their latest "totally safe" refrigerant. 1234yf, seems to be the latest hotness, perhaps our EPA overlords are thinking of banning r134a to force us into using it.

 

[gmbellew]

R4 to Sanden whith stock ac lines(for serpantine)

Went ahead with a sanden change out on my suburban. Kept original lines by picking up a sanden unit with rear line mount and adding inline #8 discharge adapter. I will get part numbers and drawing for adapter plates posted on monday. The pulley on the compressor has extra ribs, but it does not...

www.gmsquarebody.com

I did this upgrade on my 1990 suburban. definitely a lot of improvement. don't forget to adjust the low pressure cutoff switch to account for the pressure difference between r12 and r134a.

 

[fast 99]

I am honestly starting to think they just declare the previous generation of refrigerant deadly to get it regulated out of existence and force the industry to invest in their latest "totally safe" refrigerant. 1234yf, seems to be the latest hotness, perhaps our EPA overlords are thinking of banning r134a to force us into using it.

Actually some time back heard R12 wasn't causing the hole in the ozone layer, it was cyclical, duh. But now they are trying to restrict 134? It might be more about the patents expiring and a payoffs. Neither 134 or 1234 are as good [or as cheap] as R12, same with R22.

Yes, 1234 is in new cars. Think that was mandated a year or 2 ago.

 

[CheemsK1500]

R4 to Sanden whith stock ac lines(for serpantine)

Went ahead with a sanden change out on my suburban. Kept original lines by picking up a sanden unit with rear line mount and adding inline #8 discharge adapter. I will get part numbers and drawing for adapter plates posted on monday. The pulley on the compressor has extra ribs, but it does not...

www.gmsquarebody.com

I did this upgrade on my 1990 suburban. definitely a lot of improvement. don't forget to adjust the low pressure cutoff switch to account for the pressure difference between r12 and r134a.

How would one go about adjusting a low pressure switch?

 

[Vbb199]

How would one go about adjusting a low pressure switch?

You can get a gmt400 low pressure switch for your truck. Just a thought.

Its like a 92 or 92 suburban low pressure switch i think

@Bextreme04 recommended it to me i think.

I did it. It operates at r134a pressures and should fit right into your air dryer.

 

[Finkaire]

Fast99 is correct, oils are not compatible. If you switch to 134a you will need to use an ester oil. PAG oil found in current 134a systems is a corrosive and can destroy the evaporator. Replace the accumulator, hose sets are available, drain and fill compressor with Ester oil and fill with the 80% refrigerant Fast99 recommended as well as the label. On the other hand R12 is still available NOS, just make sure to keep the PAG oil away from your older system. I’m still running R12