Revert to R12

[MarkZ28]

Butane and propane work excellent also, but, if you have a big leak in the cab and it ignites, boooooom! R12 does cool better, but R134 is fine, not worth the extra cost or effort.

 

[SAATR]

Since the compressor is toast, I would recommend replacing it with a Sanden 4440. Also make sure that the condenser is a parallel flow type and not serpentine, as the parallel flow are a bit more efficient and will help cooling and head pressure, especially at idle. My thread in the Member's Trucks area has the Denso part number for the Sanden style compressor. After examining it, I'm pretty sure it IS a rebadged Sanden.

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[superdave]

A new blower motor fan may do wonders for the efficiency too. Mine gave up the ghost last year and the new one moved more air.

 

[95SUBURBANLM7]

Butane and propane work excellent also, but, if you have a big leak in the cab and it ignites, boooooom! R12 does cool better, but R134 is fine, not worth the extra cost or effort.

Ha!! Thanks for the heads up. If someone recommends either, Ill tell them where to go!

You hear that because r134a doesn't work to well in r12 systems that have been converted over. The reason it doesn't work is because it isn't designed for it.

So, since my system was originally designed for R12 it should be reverted back to R12. Right?

Since the compressor is toast, I would recommend replacing it with a Sanden 4440. Also make sure that the condenser is a parallel flow type and not serpentine, as the parallel flow are a bit more efficient and will help cooling and head pressure, especially at idle. My thread in the Member's Trucks area has the Denso part number for the Sanden style compressor. After examining it, I'm pretty sure it IS a rebadged Sanden.

This Sanden unit, how does it compare to the R4 unit? Can it run R12? I modified the TBI's A/C bracket to mount to the LM7, can the same be done for the Sanden?

A new blower motor fan may do wonders for the efficiency too. Mine gave up the ghost last year and the new one moved more air.

Thanks, Ill keep that in mind. I plan on cleaning my heater core, so while Im doing that I may just replace the motor.

 

[1500z71]

The price of R12 has multiplied tenfold. A few cans of it will run you $100, least that's the going price on eBay for old unused cans. It will probably go up too, so if you ever have a leak you'll have to find some and then break the bank for some. Converting to r134a is the most economical thing to do. I hardly doubt the difference is even noticeable let alone worth it.

 

[superdave]

When I got my truck 3 years ago, the AC wasn't working. I replaced everything but the evaporator. I cleaned that. It worked fine with R134, but the main complaint with these trucks is the amount of air the fan moves. A new fan last summer made it better. It doesn't blow your face off, but it's more flow than before.

 

[SAATR]

This Sanden unit, how does it compare to the R4 unit? Can it run R12? I modified the TBI's A/C bracket to mount to the LM7, can the same be done for the Sanden?

D'oh! My apologies, I thought you had the Vortec style accessories. So far as I know, the only replacement for an R4 is an R4, so scratch the Sanden suggestion. As far as R12 goes, if your truck is a '95 it should have been 134a from the factory, as I'm fairly certain that '94 was the last year for factory R12 AC systems in production cars. Could be some grey area there, but that's what I recall.

I would suggest replacing the condenser with a parallel flow unit, flushing all the lines, and replacing the orifice tube. Flush the evap core as well. If you have rear air, you will have to disassemble the rear AC box to replace the expansion valve and flush the rear evaporator. If your compressor had an internal failure (as opposed to just leaking) disassembly of the rear system and thoroughly flushing everything are mandatory, as debris is generally spread throughout the system during the run down to complete failure. Clean the outside of both evaporators to maximize heat transfer, airflow, and cooling efficiency.

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This is what my evaporator looked like prior to cleaning. Nineteen years of dirt, leaves, mold, and hair. It made the air several degrees colder and smelled better to boot! If you have never cleaned yours, you can bet it looks much the same.

Be sure to use the proper oil for whatever refrigerant you use. PAG 150 for R134a systems and Ester oil for R12. Once all is said and done, pull a vacuum on the system for a minimum of 2 hours, and verify that it holds said vacuum for at least 15 minutes. Longer is better, as some leaks can be very small under vacuum but very large under pressure. If you have access to a vacuum pump with micron gauge, a sub 1000 micron vacuum would be great for a mobile AC system, but below 2000 would be nothing to sneeze at. Charge the system by weight, not pressure, especially if using R134a. R12 is much more forgiving of improper charge, which is one reason people had much better "luck" using it (especially DIY) than 134a. If you don't have good scales and a good vacuum pump, take it to a shop and have them pull the vacuum and charge the system. Too much money and time invested to mess it all up with a dirty system or improper charge.

And please, please, do not convert it to R12. If you do everything I mentioned, you will get good performance out of the system, and won't pay through the nose for refrigerant.

 

[RyanMerrick]

R12 was great but is now phased out. Which is why it is so expensive. R134a does not work quite as efficiently but was believed to be more 'environmentally friendly'. However, it too will be phased out by 2020.