Re: [DML] Air conditioning

["Walter Coe" <Whalt@xxxx>]

> When you are driving, however, cool air flows nicely but
> when you accelerate, the cool air becomes warmer, and when you
> decelerate the air goes cool again.

I'm mostly just book smart on this subject with little practical experience,
so take my advice with a grain of salt:

When the air from your vents gets warmer, are you sure this is the case? Or
are you just losing air flow from your center vents ? (The door vents would
still be blowing cold air.) This indicates a vacuum leak going to your mode
switch. (This happened on my car.)

Another possibility is the following scenario: You are running your a/c on
MAX with the heater control turned counter-clockwise (or the cable from this
control is broke). By having the mode selector switch on MAX, it will send
a vacuum signal to the heater water control valve shutting off coolant flow
through your heater core UNLESS you have a vacuum leak in this circuit.
Upon acceleration, the decreased vacuum will allow this valve to open. Hot
water circulates through the heater core neutralizing your a/c. To test
this theory, run your a/c on NORM and see if the cooling ability is notably
diminished.

Another possibility is that you have moisture contaminating your
refrigerant, and this is periodically freezing up your orifice tube. Under
acceleration, your higher engine RPMs are going to run your a/c compressor
that much faster increasing refrigerant pressure which will exaggerate the
effect. (In theory, but I could be wrong.)

Hooking up a set of manifold gauges could tell you a lot. But it is hard to
use while your car is accelerating. :-) Mechanics either use a big fan to
force air through the condenser or sprinkle it with water. This makes the
condenser work at higher efficiency to simulate driving at highway speeds.

If this is over your head, have a mechanic hook up a gauge set and tell him
the system is set up like a General Motors Cycling Clutch Orifice Tube
system (CCOT).

Walt