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Critique my new AC system

Pyrotechnic on Thu July 23, 2009 12:57 AM User is offline

Year: 1977
Make: GMC
Model: C15
Engine Size: 350
Refrigerant Type: R134a

My AC system is coming together and will be ready for custom lines and a charge soon. I have a few questions and I'd like to know if what I've done and what I plan to do is correct. I've ditched the stock Harrison A6 and stock condenser. I'm also going to run R134a instead of R12. I never liked that big compressor and R12 is just too expensive.

At this point I have:

Sanden 508 compressor
16x26 aluminum parallel flow condenser
New accumulator (still sealed, not installed yet)
Stock evaporator flushed out (only the old oil came out, otherwise seems to be clean)

One question I had was about the orifice tube. From what I can collect, R134a needs a different size orifice tube to perform it's best. Is this true ? Is there a general rule to going up or down in size ? Still have not purchased this yet.

My goal is for this whole system to work as good or better than it did with the stock components and R12. How does this look on paper ? and is there anything else I need to do or consider ? Thanks.

Chick on Thu July 23, 2009 7:05 AM User is offlineView users profile

You can try the stock O tube, if cooling doesn't seem good enough for you then try the Ford blue which is one size smaller.. You might have to experiment since this is a new system, the old one was all figured out by the manufacturer....

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Don M on Sat July 25, 2009 12:30 AM User is offline

I have a 1987 Chevy full sized pickup that came equipped with factory air. If I remember correctly the AC system is the same as in the 1977 other that I had an R4 compressor rather than the A6 you have. After making modifications, my system will blow around 40 degree air while sitting still with the outside air temp above 90 degrees. I’m not running any electric fans just the factory fan, fan clutch, and shroud. I replaced the evaporator with a stock aftermarket part (old one had a leak), retrofitted the brackets to accept a Sanden compressor and replaced the condenser with a new one for a 1995 full sized Chevy pickup. The 1995 condenser is almost the exact same size as the 1987, in fact you can use the same mounting hardware. The only downside is that you must modify the radiator support in order to accommodate the different location for the input and output tubes on the 1995 condenser. Sometime in the 1995 production year Chevrolet switched from tube and fin condenser to a parallel flow condenser. If you do this make sure you get the latter model parallel flow condenser. Make sure that you take the time to fabricate something to block the air flow around the edges of the condenser. You want to make sure the air flows through the condenser and not around it. I used ¼ inch aluminum angle and foam weather-stripping to accomplish this. I used a variable orifice with R134A.

Pyrotechnic on Sat July 25, 2009 1:19 PM User is offline

Thanks for the advice. Would it be worthwhile to spend extra for the variable orifice tube ? Do they really work that much better than the stock piece ?

Chick on Sat July 25, 2009 6:51 PM User is offlineView users profile

They can cause more problems than they are worth, would never use one, but thats just my opinion... hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Pyrotechnic on Mon August 03, 2009 12:35 PM User is offline

Got one more question. I just got the lines made and now it's time to put them on. My compressor was shipped with assembly lube, so I'm going to drain/pump that out. The plan for today is to get the system assembled and ready for a charge.

Whats the rule on a new dryer/accumulator and moisture ? I had to install it while having the lines made. It probably sat open for about a half hour and then the caps were put back on.

Also, should I have a vacuum pulled on the system first to check for leaks, then add the oil, then pull it down again to add refrigerant ? Or should I just add the oil as I'm putting the lines on now. My plan to is add some of the bottle to the suction side on the compressor, then put the rest in the lines, then turn the compressor by hand a bit to work some of the oil through it, is this the proper way ?

I know that PAG oil absorbs moisture which is why I was wondering when I should add it. I'm not sure if the PAG oil I have is the DEC type, but it's Masterchem Ultra PAG 46 if it matters.

*EDIT*: I just walked outside and looked at the bottle and I was pleased to find the oil that is bought is the DEC type.

Edited: Mon August 03, 2009 at 1:28 PM by Pyrotechnic

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