I bought a retrofitting kit with the oil, a gauge and a can of 134a. I attached the fittings, turned the car on with the AC on max, added the oil and started to add the 134a but almost as soon as I started to add it, it was overcharged. I removed to cap to the high pressure valve and the o ring blew off so I took the new fitting off and put the cap on the old fitting so it would stop leaking. I did some more research and apparently I need to vacuum out the system first? Not sure how to do that and I have no idea what the high pressure valve is for because it seems like it doesn't even get used when recharging.

 

 

This isn't a DIY or something a novice could learn on their own. Best thing to do is find someone who knows what they are doing and offer him a few bucks to show you how its done.

 

Vacuum pump......Absolutely critical to performance. They look similar to an air compressor. Sucks the air out of the system by putting it into a vacuum state. It also lowers the boiling point of water from 212° (zero vacuum or atmospheric state) to ohhh let's say around -15°F. (deep vacuum or -29.9 Hg)......Any moisture that was in the system would be boiled off, since the car is sitting outside in 70° weather, which is much higher that the water's boil point.

The best and easiest explanation of how and why vacuum pumps are needed is written up here. http://www.robinair.com/acsolutions/...m/acvacuum.php

Air won't condense or aid in the cooling of an air conditioner. If a system is full of air, it will seem overcharged since the air itself is raising the pressures of the system.

The chart at the link above shows why just looking at a manifold guage with it's -30 Hg readings below zero isn't very accurate. To really know how dry the system is, you need a micron guage. Dry systems are generally in the 700-1000 microns zone (lower is better)

The high side valve can be used for filling up a car with refrigerant. It helps push the oil through during the first cycle. BUT if done wrong, you can explode the can. Causing injury and damage. The only time you can charge refrigerant into a car with the high side is with the car turned off. If it's turned on, you MUST use the low side only. Charging the low side is safe regardless of if the car is on or off. For people new to A/C work, I'd suggest sticking to the low side only for injecting anything into the system.

Vacuum pumps are expensive for the average A/C car repair. A couple of hundred bucks. Easiest thing is to find a friend who has one or simply take the car to a shop and have them do it. All you'd pay for is labor, since the only thing they do is hook the low and high side hoses onto your valves and turn the vacuum pump on. Wait an hour and you're done.

High side guage readings are handy for seeing how well your car's condenser is working. Gives a decent idea how full the system is. Troubleshooting when comparing the low side and the high side at the same time.

 

Thank you so much for the input. And NINA, I replaced it because the retrofitting kit I got came with a different one that screws on top of the older one. Seemed like a good idea until I realized I had no use for it, especially after the o-ring blew off

 

I think you're technically supposed to use both adaptors on the schrader ports. Although as long as you have one on the low side, people are going to know that you have a non stock refrigerant in there.

There are R-12 to R-134a adaptors that fit on the ends of your manifold gauge hoses. So hooking up through the low side R-134a valve and the high side R-12 valve can easily be done.

 

Adapters are fairly cheap. The mechanic at work has everything I need and the high side valve is needed if you are using the gauges (don't have an adapter, his gauges are for 134a) I want to do it next week, hopefully it works. I don't know how much refrigerant I need but I'm gonna guess it says it somewhere under the hood.

 

You also need to flush the system before hand. The two oils are not compatible with each other.

 

How?

 

any updates has anyone used COOLTop to autofrost