Climate Control Under Load - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Brendo85 · 10-30-2005, 22:16

My 95 NF(EF)I Fairlane Ghia (Auto) recently had its aircon regassed. Ever since that happened, when the engine is under load (especially on a hot day) - around 1500-2000rpm @ 60km/h in D - the aircon changes from being at the face (and/or feet) to blowing strongly up to the windscreen. The only way I can get it back is to drop under about 1600rpm. It does not occur in N,R,1,2,or 3.

Could this be a leak or a computer problem. I'm thinking of taking back to the place and seeing if they can fix it (still under warranty) but that would mean I'd be without my car for a day or two.

Also, the flap that is supposed to open under the glove box area that takes the air from inside does not open when set on inside air. It is not jammed or anything, as I can use my hand to open it (it then closes by itself).

Hope that makes sense.

fordboy98 · 10-31-2005, 23:27

It's a vacuum problem. The flaps in the system are controlled by vacuum servo motors, to which vacuum is ported via the climate control buttons (or knob). Pressing a button or turning the knob causes vacuum to operate the servo and move the flap(s) to direct the air where you want it. To ensure sufficient vacuum reserve to effectively operate the systerm, a vacuum reservoir (or tank) is used to hold a reserve supply of vacuum. This is located in the right front mudguard (I think!) and is "charged" from the inlet manifiold via a check valve. If the valve dies, the vacuum level in the reservoir may drop depending on throttle opening and cause the flaps go stupid. It's meant to be as fully evacuated as possible to ensure that the servos work under most conditions.

What's happening possibly with your car is that while the vacuum level is continually changing with throttle activity, it is casuing the flaps to move. They do this slowly over a period of a few seconds usually. When you decelerate and the manifold vacuum goes high, your flaps return to normal. When you accelerate manifold vacuum drops and the flaps tend to adopt the position they do when the car is not running. With most Fords, that means that the windscreen outlets are the ones that work.

All that said, it may be too that one of the vacuum line "plugs" that connect to the climate control, or any vacuum line in fact, may have become disconnected. That too will disturb the vacuum supply. Can you hear any hisssing coming from anywhere behind the dashboard?

Brendo85 · 10-31-2005, 23:32

Thanks fordboy. That makes sense and sounds exactly like the problem, I'll go and check some of the stuff you suggested.

smally351 · 11-01-2005, 02:00

Sounds like someone has accidentally pulled a vacuum line off when they were hooking up the A/C charge station to the low pressure service port. I have done it myself!!!

Brendo85 · 11-01-2005, 02:07

Quote:

Originally Posted by smally351

Sounds like someone has accidentally pulled a vacuum line off when they were hooking up the A/C charge station to the low pressure service port. I have done it myself!!!

Which is located where?

The only other thing that I don't understand is that this only occurs in Drive @ over 60km/h (about 3rd gear I think) and not in Netural or another of the other gear selections (1,2, or 3)

smally351 · 11-01-2005, 22:04

Quote:

Originally Posted by Brendo85

Which is located where?

The only other thing that I don't understand is that this only occurs in Drive @ over 60km/h (about 3rd gear I think) and not in Netural or another of the other gear selections (1,2, or 3)

Low pressure sevice port is in th LH rear corner of the engine bay, near the washer bottle.
Its all relevant to manifold vacuum and therefore, engine load. Hard acceleration in any gear will cause a low vacuum and the vents will change if there is a hose off.

Brendo85 · 11-02-2005, 00:46

I found a hose that was disconnected but was still sucking air. It is about 40cm (from the side of the engine bay). My next problem will be trying to find where it goes. I have temporaraly blocked the hose and will see if that has fixed it. Thanks for all the help.

Attached are some pictures of some pipes. I don't think the aircon pipe leads there though as it is about 30cm longer. Does anyone know what they are for?