'87 5KCST, AC "hunting" temp

[Fieldsj@uwwvax.uww.edu (Jerry Fields)]

Late last year, someone mentioned a GM bulletin that concerned adding a
resistor across the motor in the AC controller. I've lost it, could the
original poster please re-post? Seems to me it might help with a problem
I'm having with my AC system

The temp in my '87 5KCST seems to have to much hysterisis; it gets very
warm before changing from heating to cooling, or very cold before the
heating kicks in. Also, as the car heats up from heat gain through the
windows, the heat comes on harder; system thinks it is in cooling mode.
When the car gets very warm, the cooling will eventually come on.

I've checked the Bowden cable, replaced a questionable relay in the
controller, and checked to see that the controller motor does move when the
set temp is changed from low to high and back.

It seems to be worse when the outside temp is within 10 - 15 degrees of the
inside set temp. The controller motor doesn'tappear to  respond to small
changes in temp readings, as if it sticks or has a large hysterisis range.
Any ideas on what to look for would be appreciated.

BTW, I've been away from the list for about 5 month...its good to be back.



Jerry Fields

DoD #1697
UWW T&IR #1327