Climate control issue

WESTY1620

MEMBER
1988 CHEVROLET VAN
5.7L
V8
2WD
AUTOMATIC
295,000 MILES

My van blows air but no heat. The controls are sticky going from cold to hot and it will not change from defrost. But it gets even better. My heat gauge will not get higher the 110 to 120 degrees. I have flow through the heater core. When I bought the vehicle I was told it had a thermostat change. Any ideas I am lost?

1 Reply

HMAC300

MECHANIC
48,601 POSTS

Check to make sure both heater hoses are hot when engine warm. Check for a vacuum leak. If it has a water valve on heater hose or engine it must have vacuum to send hot water to heater. Also, must have for switching from defrost to floor. We do not have vacuum charts for that truck due to age. But start at engine and should go back to heater through firewall to control on dash then to vacuum motors on heater. Also, check for a broken heater cable if you have one I forget on that model.