I just got a 1990 F150 XLT Lariat XCab w/ 302. When I adjust the temp to cold and switch on the A/C, the A/C does not engauge. Also when I switch to hot and turn the heater on, no hot air comes out, absolutly no change in air temp. The heater core hoses don't get hot when the truck is at operating temp. The cooling system doesn't seem to have any air in it.

I jumped the A/C to force it on and I checked one of the A/C lines that goes into the condenser, it got very cold, but I still don't get cold air in the cab, not even a slightest change.

What is going on? The whole environment control seems to be screwed up. Missing vacuum lines? bad ground? Does anyone know where I could get electrical diagrams for this stuff? Thx.

 

You probably have two separate problems with the climate control.

1) If the heater hoses don't get hot, then coolant isn't circulating through them. A bad thermostat is the most likely reason.

2) No A/C. If the refrigerant line going to the evaporator (the condenser is in front of the radiator) is getting cold but you aren't getting any cold air, then it makes one wonder if your blower is even running or, if it is, if it is even pushing any air out of your vents (any of them).

Vacuum is used to change the outlet airflow ports and the recirculate door. Easy enough to check those.

Steve

 

Thanks for the info, I will check these out. I had suspected my thermostat is not working well cause the temp indicator doesn't move much after the truck warms up.

 

Oops, I meant to say the evaporator...