HVAC won't maintain a set temperature.
Ran through job 601 (Quick Test without tester) and zero faults. Works like a champ. BUT, it doesn't evaluate "quality"
Moved on to job 609 (Testing ambient, in-car and potentiometer). They all check within limits.
Checked In-car sensor for air flow pulling through. It checks okay.
I'm left with job 611 (Balancing of sensor chain). I suspect it will check okay since it simply measures the three resistors in series.
So, assuming I'm stumped to here, is it:
Amplifier (any quick checks)
Regulating Valve (only 3 yrs old) (any quick checks)
Or, what else?
Obviously I don't have the tester. I was thinking of locating the pin that sends control voltage from the amplifier to regulating valve and then run a "quality type check to see what voltages are being sent. I am aware that the amp can send out of spec voltages that can damage the reg valve.
Thoughts and help very much appreciated.
80 450 SEL
86 280 GE