Probably blocked heater matrix. Best thing to do is flush the cooling system with the best stuff you can get.
it is blocked and needs to be flushed out
The most common reason the heater is blows cold air on a 1999 Ford Winstar is a bad thermostat or blocked heater core.
Low on coolant. Stuck open thermostat. Plugged heater core. Temp blend door inop.
Same problem vectra heater only blowing cold checked water coolant and it was empty. Topped up now blowing hot just hope I not got head gasket probe
Only the fan is working, there is no gas burning (gas heater) or the electric heating element is not working(electric heater)Answeris it electric gas or oil Its gas.
No one knows if:The heater is NOT blowing - or blowing on high speed only, or... The heater IS blowing, but the air is NOT hotEither way, the "Related Questions" below will get you started
The heater is blowing out cold air only
It sounds like your switch from hot to cold is stuck on cold
no fuse check your anti-freeze level
Hose going from engine to heater core may have burst. Check all your coolant hoses for leaks.
Depending on the year, make and model check the following.............. 1. A/C heater control door. 2. Cables and vacuum lines. 3. A/C heater control panel.
There is no heater matrix for the back air vents, only and evaporator for the A/C. My suburban always blowed cold until I added an extra rear heater matrix.