The Two Minute Air Conditioner


#1

My 97 Geo Metro AC will only cool for about two mins. The air by then has gone from cold to warm. After about a 10 min rest it will restart cooling. The dealer about a year ago pronounced it to be a bad compressor but couldn?t say why. Very strange.

Strangely, when the AC is blowing warm air the compressor can be heard to be running. Alternately pulling and reseating either AC relay, audibly causes the compressor to stop and start. Swapping relays with the radiator relay does nothing new. Oddly I only see the radiator fan turn when I bypass it?s relay. The ECM computer was replace about two months ago with no change.

The dealer believed that the system had good refrigerant level and pressure. It does not seem to have leaked at all over the last year. Not confident of their measurements. This does not in my mind add up. What is going on? Thanks


#2

Take it to a local independent A/C shop. Often it will be combined with radiator repair.

   Dealers are no better (or worse) than independent mechanics for almost anything you might need done on your car.  They will almost always charge more per hour and often more for parts and supplies.  They also tend to look at repairs a little different than the independent. 

A dealer may well recommend work that strictly may not be needed, but could be connected to the problem or maybe replace a part when a little repair would fix it ALMOST as good a new.  

There is no need to bring your car to the dealer for any service other than service that is going to be paid for by a recall or original warrantee. 

I suggest that most people would be better off finding a good independent (Not working for a chain) mechanic.

#3

It’s near impossible to narrow this down without knowing what the high and low side pressure readings are.

Going from cold to warm could be caused by an insufficient charge, but this falls back on knowing those pressure numbers.
A freezing evaporator could also cause this, but that is not something that should happen in two minutes.

Assuming this occurs within a few minutes after startup with the compressor running, and after the vehicle has been sitting overnight or for several hours, I’m wondering if you may not have a blend door problem in the dash.

I’m not a Geo guy, but many doors are vacuum operated and if a vacuum pod diaphragm has a leak it could be that the blend door is not operating properly. This will then allow air to pass through the heater core, which will of course warm it back up.


#4

I had a similar problem with a Ford Aerostar van (1990). It turned out that the fan clutch was not allowing the fan to turn at a sufficient speed to draw enough air through the condenser coils. Now, I’m sure your Geo has an electric fan, but if it isn’t pulling sufficient air through the condenser coils, the effect could be the same.

My mechanic tracked it down by hooking his gauges to the system. The air conditioner would function, and then quit. When it quit, the pressure would go way up. He directed the airflow from a big fan he has in the shop into the condenser coils. The pressure went down and the air conditioning system began putting out cold air.
This may or may not be your problem, but it is an easy thing to test–take a large electric fan and blow the air stream through the condenser. If it then begins cooling, you know where to look.


#5

He directed the airflow from a big fan he has in the shop into the condenser coils. The pressure went down and the air conditioning system began putting out cold air.

That’s a good tech tip Triedaq, thanks. A tip form the pros.


#6

sounds like the expansion valve is sticking open.


#7

If you go into an auto A/C facility spouting any of Star’s completely wrong A/C info they’ll probably turn a fire extinguisher on you. It’s all bogus - and continuing with no end in sight.


#8

For gods sake Star, will you just shut up. The information you give is pure nonsense.


#9

Hey??? Where did stars post go? I’ve been triing to get his posts removed, maybe someone finally listened and removed his worthless posts.

Willey. Logged off again.


#10

Good deal. It’s just a matter of time before someone is going to get hurt following that fairyland advice.
Yep, this is ok4450; logged out yet again.


#11

It sounds like most agree that a bad compressor is unlikely and makes no sense. It SEEMS to operate normally on the hotter days suggesting to me freezing. Can it be checked for freezing by touch or by an contact type thermometer?
Will a normal check of engine vacuum also indicate the status of the AC vacuum. Thanks