I recently had my uncle check out my A/C because about a month ago it went out. Everything still works, the compressor, the blower motor, switches, I also noticed ther are no leaks under the car or in the engine. He said that when he checked the valves that he wasn't getting any pressure, and that there might be something blocking the flow of the freeon in the A/C compressor or the accumulator. Is this true? If so, how can I fix it? If not, what else could be wrong with it? Thanks alot ya'll.... :cheers: :D :thumbs:

 

Sometimes (okay, most of the time) a professional diagnosis is my solution. Today's cars including your corvette are complicated machines. Unless you have training I encourage you to take it to a professional. Air conditioning systems have expensive parts.....believe me...... :rolleyes:

 

If the compressor is turning you probably have system pressure. If the pressure was gone the low pressure cut out switch would cause the compressor to NOT function (unless some one (UNCLE) jumpered it out!

I agree, sounds like you need a good shop!

Bill C

 

Does the compressor turn as soon as you turn on the air conditioner? On the 88 the low pressire side is on the upper hose that goes into the evaporator, and the high pressure side is on the metal hose that goes from the evaporator to the condenser.

There are switches on these lines that should cut off the compressor if the pressure is too low. Assuming your switches are good and not jumpered, and your compressor is turning, you should have pressure on those lines.

Check the pressure switch and see if the compressor is kicking on. It could be that you leaked out all your pressure, but it'd have to be a pretty bad leak to go from a working AC to 0 pressure in less than a week.

For what it's worth, you probably wouldn't notice any leakage on the ground. The freon is either going to be a liquid or a gas depending on where it leaks out. I had a bad leak on my high pressure side evaporator connection (shot like a geyser due to it being stripped) and none of the stuff ever hit the ground.

 

AC systems haven't seen any changes (other than refrigerant) for the last 40 years.
They are very simple systems with few moving parts.
Buy yourself a set of manifold gauges and start troubleshooting it yourself.
Get yourself one of those little refrigeration type thermometers that you can place in your AC air outlet in the car.

If you have R134 all the following will be no problem. You can purchase 134 without a license. If you have an R12 system you will have to be certified by the EPA to handle freon. You'll also need a recovery system for the R12.
IF you have R12 this may be a good time to convert to 134.
R12 is outrageously expensive now anyway.

BTW: It is illegal to intentionally vent R12 refrigerant into the atmosphere.
You really aren't even supposed to open up an R12 system to work on it without a recovery system.
Enough of that stuff let's talk about the good things.


Here's a short course for you.

Here's the parts your system has:

1) Condensor ... the part in front of the radiator ... NO moving parts .. the part that gets warm when your AC works correctly.
2) Evaporator ... small 'radiator' inside your car.. the part that gets cold when your AC works correctly NO moving parts
3) 'Receiver/Dryer ... the part just behind your radiator that look like an aluminum 'can'. It gets cold when your AC works properly NO moving parts
4) Inlet hose..... NO moving parts.
5) Outlet hose... NO moving parts.
6) Compressor.... just a pump that circulates the freon through the system.
7) Expansion Valve/orifice tube supplies a calibrated restriction in the system so the freon can be compressed by the compressor and then expand past the orifice.
8) low pressure cut out switch.... shuts off the compressor when the freon leaks out.
9) high pressure cut out switch.... the emergency overpressure cut out switch.

You have a fan control system to control the flow of air across the evaporator.

That's about all you have on your AC system. (I may have forgotten a piece or two, I'm getting oldtimers)

This is something ANY backyard mechanic can fix with a few simple hand tools, a set of gauges and a little common sense. (R134 systems ONLY)

There's just a couple of things to check after you ascertain the compressor clutch is engaged anf the compressor is turning:

1) High side pressure..... not to important unless it's TOO high or TOO low.
2) Low side pressure....this is what you are really interested in as this has a big effect on the evaporator temperature.
The gages have a scale calibrated in temperature and pressure for the type of freon you have in your system.
You can even 'fine tune' the charge to provide optimum cooling.

If the freon is too low the condensation will usually freeze on the evaporator and the system will quit cooling. As the freon charge goes lower it will quit cooling altogether.

If too much freon is in the system, both low side and high side pressures will be too high. The system will NOT cool effectively with too much refrigerant.
A lot of folks think more freon = more cool.... NOT TRUE so don't overcharge your system.
The manifold gage on the low pressure side is an EXCELLENT indicator of the charge in the system.. it is a necessity for doing this type work. You just can't do without it. Cost about $75.

If there is a restriction in the system..(usually caused by some foreign material getting in somehow) the high side pressure will be too high.

Fingers getting tired. Hope this helps someone out there.

 

Jim

Great explanition!

Smith

You should see "right around" 30-32 psi on the LOW pressure side of the compressor. That will set you up pretty close to where it works best. The High side can be anywhere from 250-350 depending on the outside temp and how hard your system is working. If the HIGH side is in that range, I wouldn't worry about it. If it is REAL high or real LOW, then you have some other troubleshooting to do.

BC