I am trying to find out what the normal High and Low side pressures are for my 97 GMC Sierra, 5.7l. I put a gauge set up on and got 35 on the low and 200 on the high. Just trying to figure out why it will not get cold, it is cool, but not cold. Starting at step one.

Thanks

 

Those pressures, to me, look about perfect.

Your problem could be inside your HVAC unit/box. You might check your blend door. It's possible that you're actually mixing heat in with your cool air off of your evaporator.

If you can, put a thermometer in your center panel vent and see what the temp is. It should be about 45+/- degrees; as per your pressure readings.

TLDR version: My guess is its your blend door.

 

Just put thermometer on it, read only 64 on the gauge. How do I check the blend door to make sure it is working.

 

afaik, the best way to do that is to pull the HVAC and look at it. Other than that ... You could remove your control head and check to see if the wires/vacuum lines are where the aught to be.

 

found the problem, after moving blend door actuators around, by the way totally sucks to get to the on in the dash. After swapping them around, found out that was not the problem, the problem is actually the dash switch, after switching it to max and back a couple times real quick, the actuator moved all the way and allowed the full cold air to come through. arggg, now I guess I gotta find a new switch.

Well that solves the problem of why it was not getting cold. No to figure out why the voltage drops while idling in first gear. Vots go back up when driving, or sitting with the truck not in gear.

Its always somthing