AC Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TheCougarine · 08-04-2016, 09:43 PM

Hey guys, so I recently had my ac compressor go out and had my mechanic replace it and he said he converted it over to r134. Well its not cooled right since and I got to looking it over and what I understand to be the low pressure port on the passenger side is still an r12 port and the only r134 port is the one right above the compressor. So I'm wondering if this work was done correctly or does this seem weird to y'all as well? I've always been under the impression that the ac on the trucks was recharged at the port on the far passenger side not on top of the compressor and regardless shouldn't all of these ports be switched if it was converted? I'm wondering if this might be part of my problem since I had nice cold ac before the compressor went out. Was this work just not done correctly or am I missing something? Thanks in advance.

prodjay10 · 08-05-2016, 12:03 AM

It's hard to say if it was done right or not. I've heard some people say that r134a in an r12 system will never cool enough and others say that it can be done right, you have to replace and add the right parts and play with the amount of refrigerant until it's cooling just right.

Personally, I've never seen a converted system cool as well as one with the right refrigerant.

TheCougarine · 08-05-2016, 01:56 AM

Yea the all the right parts part is what's concerning me. I'm mostly curious as to why the system still seems to have an r12 fitting on it and if that's a normal thing. I always thought you charged ac through the low pressure port and that seems to be the one that's still r12
Posted via Mobile Device

prodjay10 · 08-05-2016, 04:42 AM

I've heard of some AC guys charging on the high side. Not sure why.

Bigdav160 · 08-05-2016, 05:34 AM

You charge from the high side if you don't want (non compressible) Liquid getting into the intake of your compressor. Normally you wouldn't be doing this with small cans.

I think the consensus is these trucks are not good performers with R134a. The condenser is way too small, the compressor seals leak it out, the POA set point is wrong and then you have the issue with non barrier hoses deteriorating with PAG oil. (ester oil might be OK)

TheCougarine · 08-05-2016, 11:59 AM

Thanks guys that's the info I was looking for.

TheCougarine · 08-05-2016, 01:32 PM

Update: Talked to my mechanic and all he did was fill it up with r134. What all needs to be changed for r134 to actual cool at all? Apparently just filling the system up with r134 isn't going cut it. Any advice?

engineer_gregh · 08-05-2016, 01:58 PM

The system should have been throughly flushed, vacuumed, filled with the correct oil for 134a, and the POA valve adjusted for the increased pressure as a minimum. I have two that have been converted, one with a modern condenser and one with the original. The one with the newer condenser is colder. I'm not an A/C expert but done a lot of reading on the subject. I'm sure others will chime in with their experience as well.

F.A.A.benny · 08-05-2016, 05:09 PM

Quote:

Originally Posted by engineer_gregh

The system should have been throughly flushed, vacuumed, filled with the correct oil for 134a, and the POA valve adjusted for the increased pressure as a minimum. I have two that have been converted, one with a modern condenser and one with the original. The one with the newer condenser is colder. I'm not an A/C expert but done a lot of reading on the subject. I'm sure others will chime in with their experience as well.

This is correct. it would need the poa valve recalibrated and a parallel flow condenser, and I change the drier. If you not flushing then drain the oil in the compressor and use eater oil as it is compatible with both refrigerants. Personally I would go back to r12 as its really not that expansive and with a lot less work since your system was working fine with it. You can find r12 on CL or on ebay

davepl · 08-05-2016, 07:10 PM

I have no changes from stock other than a parallel-flow condenser, and when it's not leaking it blows fairly cold air. It was converted before I got the truck, so I'm only assuming the POA valve was adjusted properly.

**truckdude239** · 08-05-2016, 08:07 PM

Quote:

Originally Posted by Bigdav160

You charge from the high side if you don't want (non compressible) Liquid getting into the intake of your compressor. Normally you wouldn't be doing this with small cans.

I think the consensus is these trucks are not good performers with R134a. The condenser is way too small, the compressor seals leak it out, the POA set point is wrong and then you have the issue with non barrier hoses deteriorating with PAG oil. (ester oil might be OK)

Not totally true , i was taught to alway charge though the low side, not sure why but it was on my ase cert test to charge though the low

Bigdav160 · 08-05-2016, 09:33 PM

All my machines charge through the high side as a default.

I can change it to low or both.

TheCougarine · 08-05-2016, 10:01 PM

I mentioned switching back to r12 and he acted like that was impossible to do and got upset that'd I mentioned it even though he'd charged the old system before with r12 so go figure there. At this point I don't think I'll be taking the truck back him. What do you guys think would be my best choice going forward since the things already full of r134

08-04-2016, 09:43 PM	#1
TheCougarine Registered User Join Date: Sep 2014 Location: Johnson City TN Posts: 311	AC Question Hey guys, so I recently had my ac compressor go out and had my mechanic replace it and he said he converted it over to r134. Well its not cooled right since and I got to looking it over and what I understand to be the low pressure port on the passenger side is still an r12 port and the only r134 port is the one right above the compressor. So I'm wondering if this work was done correctly or does this seem weird to y'all as well? I've always been under the impression that the ac on the trucks was recharged at the port on the far passenger side not on top of the compressor and regardless shouldn't all of these ports be switched if it was converted? I'm wondering if this might be part of my problem since I had nice cold ac before the compressor went out. Was this work just not done correctly or am I missing something? Thanks in advance.

08-05-2016, 12:03 AM	#2
prodjay10 Registered User Join Date: Jun 2016 Location: Phoenix AZ Posts: 429	Re: AC Question It's hard to say if it was done right or not. I've heard some people say that r134a in an r12 system will never cool enough and others say that it can be done right, you have to replace and add the right parts and play with the amount of refrigerant until it's cooling just right. Personally, I've never seen a converted system cool as well as one with the right refrigerant.

08-05-2016, 01:56 AM	#3
TheCougarine Registered User Join Date: Sep 2014 Location: Johnson City TN Posts: 311	Re: AC Question Yea the all the right parts part is what's concerning me. I'm mostly curious as to why the system still seems to have an r12 fitting on it and if that's a normal thing. I always thought you charged ac through the low pressure port and that seems to be the one that's still r12 Posted via Mobile Device

08-05-2016, 04:42 AM	#4
prodjay10 Registered User Join Date: Jun 2016 Location: Phoenix AZ Posts: 429	Re: AC Question I've heard of some AC guys charging on the high side. Not sure why.

08-05-2016, 05:34 AM	#5
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: AC Question You charge from the high side if you don't want (non compressible) Liquid getting into the intake of your compressor. Normally you wouldn't be doing this with small cans. I think the consensus is these trucks are not good performers with R134a. The condenser is way too small, the compressor seals leak it out, the POA set point is wrong and then you have the issue with non barrier hoses deteriorating with PAG oil. (ester oil might be OK) __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

08-05-2016, 11:59 AM	#6
TheCougarine Registered User Join Date: Sep 2014 Location: Johnson City TN Posts: 311	Re: AC Question Thanks guys that's the info I was looking for.

08-05-2016, 01:32 PM	#7
TheCougarine Registered User Join Date: Sep 2014 Location: Johnson City TN Posts: 311	Re: AC Question Update: Talked to my mechanic and all he did was fill it up with r134. What all needs to be changed for r134 to actual cool at all? Apparently just filling the system up with r134 isn't going cut it. Any advice?

08-05-2016, 01:58 PM	#8
engineer_gregh Registered User Join Date: Feb 2012 Location: Smyrna TN Posts: 1,153	Re: AC Question The system should have been throughly flushed, vacuumed, filled with the correct oil for 134a, and the POA valve adjusted for the increased pressure as a minimum. I have two that have been converted, one with a modern condenser and one with the original. The one with the newer condenser is colder. I'm not an A/C expert but done a lot of reading on the subject. I'm sure others will chime in with their experience as well. __________________ 1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN

08-05-2016, 07:10 PM	#10
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: AC Question I have no changes from stock other than a parallel-flow condenser, and when it's not leaking it blows fairly cold air. It was converted before I got the truck, so I'm only assuming the POA valve was adjusted properly. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

08-05-2016, 09:33 PM	#12
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: AC Question All my machines charge through the high side as a default. I can change it to low or both. __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

08-05-2016, 10:01 PM	#13
TheCougarine Registered User Join Date: Sep 2014 Location: Johnson City TN Posts: 311	Re: AC Question I mentioned switching back to r12 and he acted like that was impossible to do and got upset that'd I mentioned it even though he'd charged the old system before with r12 so go figure there. At this point I don't think I'll be taking the truck back him. What do you guys think would be my best choice going forward since the things already full of r134



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