AC Condenser - Should I use New Or Original.

[v3500bigred]

Hello My 1st Post.
1991 V3500, 350
Any suggestions on which condenser to use.
I am switching to 134a and replacing everything but evaporator.
The new condenser is very light and looks very fragile.
The original looks bomb proof and is leak free and cleanout good.
I spend a lot of hours banging around on BLM and forest service roads in Rockies, Utah etc.
The new on looks like it wont last in that environment.
Suggestions?
I could try the new one and if it fails switch it out for the original.
Or use the original if it condenses adequately.
Thanks

 

[bucket]

If the new one you got is the modern crossflow type, it should work better with the r134a.

 

[edgephoto]

I have converted hundreds of old R12 systems to R134a. I worked as an auto tech back when they phased out R12. Converting was simple. Evacuate the R12, remove the compressor, drain out any oil and measure. If you can, replace the orifice tube calibrated for R134a but the R12 one will work. Replace the accumulator, screw on the fitting adapters and then put the proper oil back in the correct amount.

Pull a vacuum for 15-30 minutes to boil any water out, if you have the time let it go for an hour. Then shut the gauge and make sure it holds vacuum. If it does, recharge it with 75-85% of the weight it calls for in R12 with R134a. Your system will work fine.

You will hear all kinds of theories, myths and advice like replace everything because the efficiency of R134a is not as good as R12. These old systems are so oversized to begin with any loss of efficiency you will never notice. Don't waste time or money on parts replacement unless they have failed.

 

[ali_c20]

If the original parts are not broken I would use them.

 

[fast 99]

I have converted hundreds of old R12 systems to R134a. I worked as an auto tech back when they phased out R12. Converting was simple. Evacuate the R12, remove the compressor, drain out any oil and measure. If you can, replace the orifice tube calibrated for R134a but the R12 one will work. Replace the accumulator, screw on the fitting adapters and then put the proper oil back in the correct amount.

Pull a vacuum for 15-30 minutes to boil any water out, if you have the time let it go for an hour. Then shut the gauge and make sure it holds vacuum. If it does, recharge it with 75-85% of the weight it calls for in R12 with R134a. Your system will work fine.

You will hear all kinds of theories, myths and advice like replace everything because the efficiency of R134a is not as good as R12. These old systems are so oversized to begin with any loss of efficiency you will never notice. Don't waste time or money on parts replacement unless they have failed.

Agree, except today original rubber parts are 40-50 years old. Would be advisable to replace with barrier hose and all new o-rings. Another consideration is increased efficiency of new design compressors.

 

[Hunter79764]

Newer microchannel condensers can reject a lot more heat than a fin and tube style, no myth or rumor to it. I was an engineer for Lennox HVAC on projects going from older to newer style, they certainly work. The question is, do you need it? Most single cab trucks will never notice the difference, but on a double cab run in hot areas, you might benefit from the new style. A suburban in hot areas will always get a vote for the new style from me. Either one, airflow will be your hero, especially if you do a lot of low speed driving. If you can do electric fans, I'd recommend them. Or at least a "pusher" fan if you want to keep mechanical fan for reliability in the back country. As for durability, if I needed one to work after getting hit with a forklift, I'd choose fin and tube all day, but better yet, don't hit it with a forklift. These have been on cars for 30+ years, I haven't heard of too many cases where the condenser fatigue failed.

The other way of looking at it, are you generally happy with the old AC? If it "Wasn't Cutting It" before, you definitely need to upgrade the condenser, losing a little capacity with the refrigerant change is moving you the wrong way and you need all the help you can get. If you never had to run it on high for very long, the hit you take on 134 vs 12 probably won't be a big enough deal to matter which condenser you use. Either way, your new charge might follow the old rules of thumb, but better to charge to temps and pressures, and maje sure you tune the low pressure cycling switch to take full advantage of the R134.

 

[Finkaire]

Either way you go use an Ester oil, PAG is a corrosive and may take out your evaporator FYI

 

[edgephoto]

Newer microchannel condensers can reject a lot more heat than a fin and tube style, no myth or rumor to it. I was an engineer for Lennox HVAC on projects going from older to newer style, they certainly work. The question is, do you need it? Most single cab trucks will never notice the difference, but on a double cab run in hot areas, you might benefit from the new style. A suburban in hot areas will always get a vote for the new style from me. Either one, airflow will be your hero, especially if you do a lot of low speed driving. If you can do electric fans, I'd recommend them. Or at least a "pusher" fan if you want to keep mechanical fan for reliability in the back country. As for durability, if I needed one to work after getting hit with a forklift, I'd choose fin and tube all day, but better yet, don't hit it with a forklift. These have been on cars for 30+ years, I haven't heard of too many cases where the condenser fatigue failed.

The other way of looking at it, are you generally happy with the old AC? If it "Wasn't Cutting It" before, you definitely need to upgrade the condenser, losing a little capacity with the refrigerant change is moving you the wrong way and you need all the help you can get. If you never had to run it on high for very long, the hit you take on 134 vs 12 probably won't be a big enough deal to matter which condenser you use. Either way, your new charge might follow the old rules of thumb, but better to charge to temps and pressures, and maje sure you tune the low pressure cycling switch to take full advantage of the R134.

If you need to replace parts because they are worn, leaking or in rough shape than I agree, replace with modern design. If you need to replace hoses, of course use barrier hose. I think that is all you can find anyway, now.

My point was if you were happy with the system using R12 and you are just converting or doing a minor repair then why throw out perfectly good parts. If you are resurrecting a system that has been open to the elements for years, well that is different.