Air conditioning Help Please

[Gunny65]

When I bought my 89 Blazer the AC didn't work. I mean, it seemed to turn on correctly but no cold air. A few years later, today, I decided to check the system out.

Everything on the outside looks in good shape, hoses, connections, electrical, etc. One hose connection was loose but barely. I imagine that is why the system was not getting cold. It was empty via the loose connection. It was the connection right before going into the top of the evaporator.

I turned the AC to max, the fan to hi, and temp to cold. I could hear the vaccum working and flaps adjusting. A lot of air was coming out of the vents but it was hot air of course. I jumped the compressor via the low side switch and the clutch kicked in so the compressor clutch seems to be working. No wierd noises when I jumped the compressor. A bit of rust dust but that was due to inactivity for who know how many years.

Since it was already empty I bought the ID Q Recharge and Retrofit Kit. It has 134a, Oil, and sealant. It also has the adpaters for using R134 fixtures. Probably not the best route to take but I took it. My system say it should be charged with 3.25 lbs of R12. So I used the 85% rule I used in the instructions of the kit (3.25 x .85 = 2.76 lbs of 134a needed to replace the R12). That comes to about 44oz of R134a needed to get the system working. I installed the R134 fittings on the low and high schrader valves, then set the selector switch on the retrofit kit to ambient outside temps, then started filling the system.

I never did get any pressure to register on the retrofit kit regulator but I know R134 was going into the system. I didn't try to get reading when I jumped the compressor clutch as it was just a short quick test. I used approximately 44oz of 134a and the compressor clutch never kicked in or even seemed like it tried. I looked the system over and didn't see any leak areas so I know the system has to have SOME pressure in it. I just don't know why it didnt register on the kit's fill guage.

Now I am stuck. Not sure what to do. Suggestions please?

 

[4xcrazy]

Jump the switch again for a few minutes and see if the air cools down at all, any little bit, you're absolutely sure, the freon was going in to the system, you're sure there is pressure in the system now...

I seem to remember having to remove the shrader valve in the r-12 port, then install the 134 valve adapter. Been awhile since I messed with them like that though.

You really should have some sort of better quality gauges on the system to see the pressures.

 

[bushmaster]

my car has a slow leak and i have to top it off every season, its not empty but low and it generaly uses the whole can,
so maybe you need more?

 

[Gunny65]

Jump the switch again for a few minutes and see if the air cools down at all, any little bit, you're absolutely sure, the freon was going in to the system, you're sure there is pressure in the system now...

I seem to remember having to remove the shrader valve in the r-12 port, then install the 134 valve adapter. Been awhile since I messed with them like that though.

You really should have some sort of better quality gauges on the system to see the pressures.

I am absolutely sure the freon went into the system. Can got cold, weight went down, nothing blowing out the sides or hoses that I saw or dectected afterwards.

This kit has a vavle that screws on over the schrader valve for both the low and high side. The threads are sealed so no leaking there either. Besides the R12 valve is part of the system. You would have to cut it off, open the system to outside and weld a new vavle on for 134. At least on the blazer anyway.

The kits guage never showed any pressure what so ever. Even after 44oz of freon. Not sure why. I know the low pressure hose got cold about half way to the compressor, that was about it. Of course the accumulator got cold. I think it is called the accumulator. You know, where the low side valve sits.

 

[Gunny65]

my car has a slow leak and i have to top it off every season, its not empty but low and it generaly uses the whole can,
so maybe you need more?

The system was empty so I put 44oz or just about 2.76 lbs of freon into the system.

 

[4xcrazy]

Jump the wires again, see if it kicks on, could possibly be a bad pressure switch.

I just had to replace one on my mothers ac system in her '94 truck due to this. Not difficult and not really too expensive, think it was under $10 or so.

 

[Fordum]

Gunny, I hate to say this, but if the gauge shows no pressure, it usually means there is no pressure in the system.
And with no pressure in the system, the pressure switch is not going to kick on the compressor.

The thing to remember is that basic laws of physics still apply even to Freon. Its just like the radiator. If you keep pouring water in, but it never fills up, then the water is running out somewhere.
The only difference is, with Freon, it does not puddle up and get your feet wet......

The fittings on an AC system are almost exclusively O ring fittings. When you tightened that loose fitting up, did you look first to see if there was an O ring in place?

It sounds like you have a big leak somewhere. Look for a cracked or broken line on the condenser, or where the evaporator lines come out of the firewall.

I suspect that something major is broken off. Maybe the evaporator is split. Where ever it is, it must not be too obvious or you would see it.
But the hole is big enough that you cannot build up pressure and you do not hear the hissing.

Since your recharge has oil in it, look for oily spots.

 

[77 casa grande]

You have a leak somewhere and it needs to be adressed.
Buy yourself a o-ring kit and change them at all of the connections, including the ones on the compressor. After several years of not working they can dry up and crack.
Try to get hold of a vaccume pump and a set of gauges.(buy ,rent, borrow) to check for leaks. If your system holds vaccume,it will hold pressure. And its alot cheaper than using gas to check for leaks. You'll also need it to evacuate the system prior to adding gas.
Replace the orrifice tube, check the old one for debris,some fine aluninum dust is ok but any shavings or black particales mean your compressor is on its way out.
Also replace the accumulator, as the drying media is now spent.

What are your intentions with this truck? If you intend to hold on to it, then it may pay to replace the whole system. The truck is 23 years old some of these parts are nearing there end.

 

[Gunny65]

Well, I couldn't find a leak but you all are correct, there is one somewhere. I just can't find it. Since it took about 7 to 10 minutes per can I figured the system was okay. However, I guess it is time to tear into it and fix and replace things. I plan on keeping this truck for some time so fixing the ac is warranted.

So should I replace the system with new or just rework what I have? Its probably obvious I haven't done this before.

I will be reading AC threads tomorrow . Joy!

 

[Fordum]

If you have not seen any oil anywhere, I suspect it may be the evaporator in the dash. Pretty much all the rest of the system is visible.
You really need a leak detector.

Soapy water in a spray bottle will do in a pinch for the outside stuff. But you need to see if you can find someplace to borrow or rent an electronic one.

The leak you have should be findable with the soap, since it must be pretty good size.
But, after you find and fix it, then you need to find any small ones.

With the system as open as it is and for as long as it has been, you need to replace the drier, probably the orifice tube, and do some good vacuuming after you get all the leaks out.
Freon will react with the moisture in the system to produce acids that will ruin your aluminum parts if it does not freeze up the orifice tube first and cause it to stop cooling from time to time.

First, find the leak, and see what that tells you. If its just an O ring, then you may be able to get buy with the drier and orifice tube and new O rings.
But, if its a split hose, then suspect the other hoses too.

If the evaporator has split, then examine it carefully. Odds are you will find it paper thin which means that the system has been run with moisture and it has eaten the aluminum parts out from the inside.

All in all, find that leak first before making any decisions about the state of the system.