A/C Problems

["R. Cummings" <cumm@flash.net>]

On Tues. Sean writes:

>Subject: A/C Problems 90q20v

>Just tried my A/C for the first time. Everthing seems to be working
>properly, but when the compressor cycles on and off, it causes the car
>to jerk back and forth. The A/C cycles every 5 seconds or so and the
>driveline jerking is worse in 1st, 2nd and 3rd gears.

The compressor should never cycle more than about 4 times per minute. I
assume your car has a CCOT (Cycling Clutch Orifice Tube) system with the
accumulator on the low pressure side and mounted on or near the firewall as
opposed to an expansion valve system with the receiver dryer on the high
pressure side mounted near the condenser.

Fast cycles are normally caused by a rapid decrease in low side pressure due
to low refrigerant charge in the system.

This can be easily checked by feeling the accumulator (a can slightly fatter
than a tennis ball can mounted near the firewall with a large hose that goes
to the compressor). The accumulator should be very cold (almost freezing)
when the clutch cycles off.

Low charge is the cause of this complaint 99% of the time. If this happens
to be the 1% exception let me know and I will give you the rest of the story.

Bob Cummings
87 Coupe GT