Air Con Blowing Hot

[vg1037]

Hi

 

I recently bought a 1996 v6 2.8 auto Galaxy. When I bought it the air con/climate control was working ok although not particularly freezing cold.

 

It has now given up the ghost completely and all it does is blow out boiling hot air whatever the setting. I have had the system checked for leaks and re-gassed by a local mobile Air Con guy but still no joy. He suggested it migt be a problem with the in car sensor to the left of the controls so I have replaced the whole control unit with a secondhand one. This has still not cleared the problem.

 

I'm going to change the pollen filter today as it looks dirty but not sure if this will make any difference.

 

Can anyone give me some advice as to what to look for next.

[bradsyerbud]

Iv had the same problem as you. Iv had it checked by 2 garages and they have both come back with the same reply, compressor failure. And i hope your sat down for the next bit cause your looking at about

[vg1037]

The guy who did the re gas said he was certain the compressor was working fine as all the pipes etc get cold like they should do.

 

The control unit doesn't flash on start up and no fault codes were showing on his computer.

 

Could it be anything else that is causing the problem?

[Scorpiorefugee]

If yours is the full climate system than it could be that you have a problem with the servos that operate the heater. I.e., it may be blowing hot air from the heater matrix even while it is set to blow cold. Not easy to fix but it might be interesting to see what happens on a hot day when the engine is cold.

 

I can't make any suggestions on how to diagnose or fix this but if the air con pipes are getting cold it does suggest that it is an air flow problem.

 

It is also possible that you just do not have enough gas in the system. It does need to be checked properly and, as far as I know, the only way to do this is to take it all out and put back a measured amount which is considerably more than for a normal car.

[vg1037]

The Air Con has only just been serviced and re-gassed so I don't think it's a shortage of gas casing the problem.

 

The air con blows hot air almost straight from start up.

[Scorpiorefugee]

If you've set the system to blow cold air the worst you should get is ambient temperature air, i.e. coolish. If you're getting hot air then it has to be coming from the heater or the aircon is working in reverse. Since the latter is unlikely, either your hot air is as a result of sun on the bodywork and it will cool down a bit after a while or you heater control system is very confused.

 

You really do need to be sure of your symptoms or you are very likely to be ripped off.

 

And do you really trust the garage that "filled it up". What did they use?

 

There are sensors which detect pressure in the system. If one of those is faulty or a wire has been pulled off, that could be the only problem. Simple test here is to listen for the pulley clutch being pulled in when the air con is activated. It is a very audible click from the front.

 

And you really do need a full system before it will work properly. Checking pressure is a waste of time.

[vg1037]

I had a friendly mechanic have a look at the car today.

 

After checking everything it seems all the Aircon components are workng fine, compressor, pump etc and he is fairly certain the fault lies inside the heater box. The two motors on the side turn but don't seem to be doing anything inside the box.

 

Is this likely to be the cause of the problem and if so is there somewhere I can get a secondhand/recon heater box unit

[dmrolyat]

i have EXACTLY the same problem on my 1998 2.8 V6 Auto Ghia X (with climate control)

I have taken the servo motors off the side of the box (basically there are 2 on the right hand side). The lower one operates on a large toothed (cogged) half moon which is for the air flow direction (footwelll, windscreen, vents etc).

The upper one operates on a cogged wheel which is almost entirely hidden inside the matrix and only a small part can be seen through a hole where the servo motor operates on this wheel.

When removed, both servo motors operate normally, and changing the temp or flow direction operates the appropriate servo.

However, when i manually rotated the cog which controls the heat, it failed to make any difference to temp and consequently i have established that the fault must lie within the matrix unit. I assume this controls a valve which allows the coolant to flow through the matrix and thus heat.

I am guessing it is a fairly big job to remove the matrix completely, but i guess that is probably the only way to sort the problem.

Alternatively, because of the high costs of repair/replacement, i have considered bridging the inlet/outlet pipes connected to the matrix inside the engine bay against the bulkhead, and thereby not passing coolant at all through the heater matrix. I know that would mean no hot air in the car, but at least i wouldnt be sweltering everytime i drive it!

If anyone else can shed further light on the problem i would much appreciate it!

 

 

Many thanks