R134a conversion

[chief_shotts]

I am in the midst of converting my system to r134a. I see alot of people talking about high pressure cutoff switches being necessary for r134a systems. I also see a lot of people who convert with no mention of using a HPCO switch. What's the deal? Is it necessary? And if so how do i go about adding it?

 

[Sad Sack]

I converted my '85 over to R134 with just a new compressor, orifice tube and accumulator. The guy helping me said a new condenser would be a good item to throw in too but truck cooled down enough for me to be happy as-is with those three installed items.No HPCO switch needed. Your results though may vary.

 

[chief_shotts]

I converted my '85 over to R134 with just a new compressor, orifice tube and accumulator. The guy helping me said a new condenser would be a good item to throw in too but truck cooled down enough for me to be happy as-is with those three installed items.No HPCO switch needed. Your results though may vary.

Excellent! Thanks for the input. I installed new everything since my system was open for an unknown period of time.

 

[Chevydad]

I installed the whole AC system, no high pressure switch. It does have a low pressure switch.

 

[Ricko1966]

I converted my '85 over to R134 with just a new compressor, orifice tube and accumulator. The guy helping me said a new condenser would be a good item to throw in too but truck cooled down enough for me to be happy as-is with those three installed items.No HPCO switch needed. Your results though may vary.

Install a pusher fan in front of the condenser. And wash the condenser.

 

[dd1990]

I converted to r134 with a sanden compressor with no high pressure switch. The Compressor had a relief valve so if the system is over pressurized you will just loose some freon. That being said if you use the dual gauges and don't overfill I wouldn't worry about it.

 

[edgephoto]

Some systems came from GM with the high pressure switch and some came without. My 1987 V3500 did not have one from the factory.

Since you replaced everything make sure you have the correct amount of PAG oil and charge it to 80-85% of the R12 specified charge. Don't overthink it.

 

[chief_shotts]

Some systems came from GM with the high pressure switch and some came without. My 1987 V3500 did not have one from the factory.

Since you replaced everything make sure you have the correct amount of PAG oil and charge it to 80-85% of the R12 specified charge. Don't overthink it.

yes i believe its 10-11 oz of pag and 80% of 3lb 8oz... so about 45 oz of r134a