Hello.

I have a 1980 C3 with stock AC that was converted to R134 and works but not great.

• The surging on the compressor has the fan belt humming and it’s annoying. Also
• can’t get vent temp under 58 degrees and weak fan.
• condensor gets very hot taking engine temp from 185 to 210 when running AC even with Lincoln Mark VIII fan.

I was considering an upgrade to vintage air but I have a limited budget.

has anyone seen improvement by going to sanden compressor with parallel flow condensor? If so can you advise what you used?

I called vintage air but was told that the compressors they sell are made to work with their system and don’t push enough volume for stock evaporator.

thanks

 

R12 Freon is still around but in limited supply in this country. It is still being produced in some countries. Last I heard Mexico was still producing it. I would try to locate some with some spare cans if you plan on keeping your car.. I saw some on eBay recently.

 

I’m already on R134 and want to stay that way. Just want to get better performance.

 

R4 compressor lurch or surging sensation and the belt slap or compressor groans are mount issues. When the system has a high head pressure and the load is high, especially when engine bay temps are hot, these symptoms are common. Make sure the lower mount bolt (the long one) is sleeved to the hole in the compressor body at the front and the rear. GM even had a technical bulletin about this back in the day but I think the issue is more common now because modern replacement R4 compressors are "universal" and made to fit anything they are used in whether GM cars, a Mercedes, or even construction equipment.

If the stock system is properly set up and functioning it should be blowing 40-45 degrees out of the vents. Doesn't matter if R12 or R134. Your system is not working right but you know this. There are so many threads here on proper A/C troubleshooting and repair that I won't begin to ask background questions or make suggestions.

Not sure what Lincoln fan your are speaking of and how that mod factors into your problems.

My experience as a point of reference.....stock 1978 (same HVAC system as 1980) was not working when I got the car. Diagnostics showed the compressor was bad. I went though all of the cabin HVAC components to make sure the controls, electrics, vacuum parts, and so on did what they were supposed to do. Then I dealt with the engine bay side. When a compressor fails it typically runs the compressor trash through the system so I flushed the entire refrigerant system (hoses, lines, evap, condensor). Replaced the R4 compressor, accumulator, orifice tube, and o-ring seals. Vacuum test was good. Charged the system to ~85% of the R12 spec with R134. System now blows 40 degrees. I use the A/C probably 90% of the time I drive the car and it gets driven. Coolant temp never changes regardless of the A/C use or outside ambient temperature and I drive often in 85-100 degree temps. I did this work 3 years ago.

The devil is in the details. Not just a cliche. You have to want to fix the problem and not just throw parts at it. Get a set of A/C manifold gauges and do a lot of reading. You can get what you have working again.

 

Ambient air temperature minus 30 equals evaporator temperature measured at the discharge ducts. Florida right now.......95 degrees minus 30 equals 65 degrees evaporator temp.

 

Here are my thoughts. Please recognize that I am NOT an auto ac expert. But I have chatted with several who are.

There's a good chance you have charge contamination, Excess water vapor or air mixed in with ur R134. Did the system sit open for any amount of time? (as in, an unrepaired leak?)

When was the last time your dryer/receiver was replaced, ever?

Pulling a vacuum on a system cannot "boil out" all the water in a soaked D/R. It's an irreversible chemical reaction. It was fashion 40 years ago to do overnight evacs. No longer. Perhaps the D/Rs of that day worked differently, chemically. Or else the vacuum pumps sucked. Or else a lot of techs just didn't have any better ideas on what to try.

The purpose of the dessicant in the D/R is to getter that last 1-3% of water vapor that pulling a high vacuum doesn't catch. (In a vacuum, water boils at room temperature, which is why you don't want a leaky Space suit!)

If this is all going to be DIY you could start by replacing the DR (cheap!) do a quick leak check with pressurized (dry) nitrogen, and PROMPTLY evacuate the system and charge it. Or skip the pressure test, and just see how well it holds vacuum, and charge with refrigerant containing dye. Things being the way they are, I'd just plan on a second round, after leak checking with a sniffer and black light, etc.

Glynn something-er-other down in Louisiana, a top AC Pro on IATN.net, told me, in his strongest southern drawl, "It ain't the quantity of charge nearly so much as the quality!"

Water obviously doesn't compress, and compressed air cannot carry nearly as much heat away as refrigerant. Unlike refrigerant you're not gonna liquify compressed air putting it through the condensor.
The presence of both will raise the compressor temperature, make it work harder.

Excess water can also turn refrigerant oils into mud.

You COULD take it to an auto AC pro and have them "test" your charge for you, but my experience is those guys want you to
leave them alone, let them do the entire job A-Z, and then pay a $$$$ bill afterwards without complaint. And half of THEM are
incompetent, having merely passed an ASE memorization quiz.

When you charge it, you might want to add a little additional oil. That's an entire other topic...

I have my doubts that a replacement compressor or condenser is gonna be a magic bullet unless that's part of a completely new,
engineered system. e.g. Vintage Air.

If you're already way out ahead of me in terms of practical experience, knowledge, charge quality, etc. then by all means throw a few parts at it but be sure to get back to the rest of us us on how it works out.

p.s. I would also check your fan shrouds, fan clutch, etc as rocketing up to 210 is.... annoying, at least.

 

Vintage Air is a complete waste of money on a Vette that has factory AC. Need to step back and research what you have and what is incorrect, my first question is why do you have a Lincoln Mark VIII fan on your Vette. Also given you are on a budget can you do this work yourself? Special AC tools are pretty cheap at Habor Freight.

While the below link is for a 1973 AC system it will give you some insight on just how inexpensive getting a factory AC system back up and running is if you have the skills to do the work yourself.

https://www.corvetteforum.com/forums...completed.html

 

I plan on doing work myself. I went to electric fans last years but with dual spa’s I’d go from 185 to 240 with AC running. I updated to Mark Viii fan because of its high CFM rating. It did help so I can run AC now in hot south florida but it does still raise engine temp to about 210.

I planned on trying to improve AC performance and lower condenser temp to help with cooling and then replace blower with c4 blower since it also is weak. I’ve already ensured that all vacuum circulation doors are in proper position and no mixing of outside air.

 

Seems condenser working..
check your hot water shut off…or add them..
my concern would be the conversion.. seems to me that requires mineral oil removal/ flushing along with new dessicant and correct oil.
pull vacuum and charge by gauges or weight at 80% r12…
maybe old oil in there, too much etc..
pics of you fan assembly and shrouding are helpful.
you can always use water hose to cool condenser and check temps..

you can buy all the gauges , vacuum pump, and parts for what some charge to service.
i think 25f rise is excessive for a proper cooling system. On hottest day mine goes up about a needle width

 

I disagree. In the link you provided that person lucked out that all the hose seals, condenser, and everything else was in good enough shape to hold a charge. I was looking at a 51 year old system with a lot of unknowns, and I saw pretty quick how much of a rabbit hole I would be going down. I chose to put in VA system so I would have a complete known entity. Oh, and the stock system even when working properly is pretty lacking in airflow, for any number of reasons. The VA system is head & shoulders above it in that respect.

 

Below is an older Corvette Magazine article on R-12 to R-134 conversion.

77-82 R12 to R-134 Conversion

 

If it was here......I would check first for low side pressure.......should be in the low 40's.......if that is good then feel the actual airflow out of the vents on high.....is it blowing hard? If now.....then you probably have debris in the Evap box blocking flow.......use a boroscope to inspect.
If that checks out...then something in the closed system is making it inefficient.......bad Reciever/Dryer....partially blocked orifice tube, etc.......
The Mark VIII fan is very powerful......that shouldn't be an issue.....but have you looked between the condenser and radiator to see if there is any debris impeding flow?
As stated above.....a methodical approach with attention to details is the order of the day here.......

Jebby

 

This was mine when I took it down to clean it,

Neal

 

the rain gutter screen at each lower corner of the windshield are critical to try and prevent this

Neal

 

 

Another: https://www.corvette-restoration.com...-r12-to-r134a/