I need to do the AC on my '93 C4. A couple years ago I recharged the AC in my 1990 Land Rover, I used this stuff called Red Tek that came in a kit for $75. I think it's actually propane. If I can find it again I'll probably do the same for the C4. The Red Tek got me thru the summer in the Rover, I didn't want to redo/refit the system for the new stuff.

 

I don't care how cold it gets and/or how cheap it is. NFW would propane be in my car.

 

There is a very good chance that in the not too distant future, you might not have a choice in the matter. A few years ago, R22 was banned in favor of R410 because R22 had a very high GWP(global warming potential). R410 was to be the planet's savior. Guess what? The populous state on your west coast has decided that by, I believe 2023, R410 will no longer be an acceptable refrigerant because it's GWP is now considered too high. Manufacturers are struggling to find cost acceptable alternatives but at the present, hydrocarbon based refrigerants such as propane (R290) are one of the few alternatives to HFC refrigerants. R134A used in automotive and small scale standalone units is also on the chopping block. Automotive companies are phasing in the use of R1234. Care to guess what the cost of a recharge is? Propane is actually in more widespread use than people realize. One particular use is in vending machines. Irregardless of the future of refrigerants, I sometimes grin at those who have no problem traipsing around with 20 gallons of highly explosive gasoline yet cringe and panic at the thought of 3 aerosol cans of propane.

 

Jared, I tested my a/c today because its very hot and all I got from it was hot air, I have a 92 with as far as I know the system has never been charged. I also have 8 cans of old R-12 with the hose and connector no gauges. I'm thinking of charging it myself and wanted to know if it's okay to charge without gauges?

 

I did mine without gauges. The key is knowing what the total capacity is of the system, and what of that capacity is oil. I also strongly recommend drawing a vacuum on the system to evacuate any moisture that may be in there. Drawing a Vacuum is not really necessary unless the system has been open to the atmosphere at any point in time. I decided to vacuum mine because by completely evacuating the system of all refrigerant, I knew exactly how much I needed to add.

A lot of people place a temperature gauge in a center vent and add refrigerant until they reach a desired temperature at max AC settings.

Jared

 

I would have gauges because I want to know what pressure it has before I waste the R12 by dumping it in if there is a leak.

 

Another good reason to draw a vacuum. Pressure gauges are kind of useless unless there is something in the system to measure.... hence if it has a leak and the system is empty, nothing to measure.

Drawing a vacuum is a much better way to determine if you have a leak, if it doesn't hold a vacuum then it has a leak.

Jared

 

Wouldn't you want to get a gauge on it to see if you even have anything in the system? Other than that, I totally agree with you that if I must DIY, I'd make sure I draw vacuum and have a proper system to refill it.

 

Pull the cap off the charge port and push on the valve. If **** sprays out or it hisses, there is something in there.

Jared

 

Vacuum leak testing is a very poor way to leak test. You are testing with -14.7 psi and you haven't got any way to locate a leak if you have one.
Pressurize the system, i like dry nitrogen, and leak test. When you know it doesn't leak, blow that down and evacuate it. Then weigh the charge in.

 

I had a vacuum pump, and a lot of guys use vacuum pumps.

I guess next time I need to leak test an AC system I will just run down to Wal-Mart and grab a box of dry Nitrogen, 3rd shelf, right next to the rocket fuel.

Jared

 

hell I got my 84 about 2 years ago I see they coverted it to r134 so that what I put in it is cold it was down to 20 pounds when I added one can at 45 pounds now

 

I don't judge. Use some 134a but test it with pressure. Hell, i've used compressed air. Just use your vacuum pump for its real purpose.

 

Jared, thanks for the quick reply but how can I draw the vacuum on my system?

 

Now that's funny I don't care what anyone says.

 

I am changing compressor and dryer on my r12 system as it sat and 12 ounces brought to life the system except compressor noisy as hell so probably on way out..that accumulator dryer looks like a bear....any tips from anyone?
number one buy gauges. Mine needs adapter for high side which im still waiting for.
bought 2 cans r12 ebay 75 bucks...one left...
not sure what im going to do to remove r12 in system..i would let someone reclaim it if for free..otherwise..add some sunscreen.
just scored 6 14 ounce cans craigs list from someone 10 miles from me for 80 bucks..ive got 6 pounds now..im keeping r12..and one quart ac delco amazon mineral oil ac.
also have robinaire pump..you need to pull vacuum and see if there are leaks before charging anything.
all the gauges and pump good quality 200 bucks and you keep them..

 

Harbor Freight sells a cheap vacuum pump that works remarkably well if you have an air compressor with the CFM to operate it.

I have 2 30 gallon compressors teed together before my air dryer. They are all on independent breakers so the second compressor only gets used when I am sandblasting usually. Only running one compressor I was able to get down to 20in of vacuum, with the second compressor running I was able to get 28in of vacuum.

https://www.harborfreight.com/air-va..._q=vacuum+pump

It has multiple uses as well, I made a vacuum chamber out of a half gallon glass jar and have used it to perform brake fluid flushes and power steering fluid changes.

Jared

 

They are used for guys who have difficulty rising to the occasion also so what exactly is the real purpose?

 

Jared, I appreciate all the experience y'all have on this topic and I hate to slow you guys down, but for an old geezer I haven't been around the same block as you folks. Thanks for the HF link I might just order that pump but all I have is a 5HP 20gallon air compressor . I just tried my A/C system and noticed that the air compressor didn't even engage and it's blowing hot air. Doing it your way seems complicated, my 92 hasn't ever been charged and at this point I'm temped to just pump in a couple of cans of r-12 and see what happens, do you think the compressor will start up if it gets any Freon, and if it doesn't does that tell me to get a new compressor.

 

I know some people seem to think only they can work on the magical C4 and do it right but might I suggest you get a professional to diagnose exactly what is wrong before throwing good money after bad?