How to change between heat and a/c - Cars & Trucks

The heating coil is probably getting plugged up. You may have heat at idle or slow speeds, but once you get going, there is not enough coolant going through it to stay warm. Get the system flushed or replace the heating coil.

Check vacuum hoses. There's one between engine and firewall at the passanger side that operates ur heater. This little creature dries up due heat expossure and cracks causing a vacuum leak that will trigger ur check engine light as well..

i think the heat control in this is electric and a little motor moves the damper open and closed you can check the two motors but its probable the heat control unit check and see if you have power going to heat unit

have you changed the 2 heater hoses? They can become plugged

maybe if you never changed it i would change it and flush radiator

Check your coolant level! The coolant has to be fairly full in order to heat the heater coil. If your coolant is at proper level and your mixture is good (around 50/50) your thermostat may be stuck open. This should have nothing to do with your latest oil change.

If you have changed you said the olny thing left would be thr thromostat is not opening for some reason Then no heat would get from the engine back to the radiator But im supprised that your not having a over heating problem What dose the engine temp gauge read when the engine hot and idiling

change your thermostat you probably have a old one.

The heated seats have relays that run them. Not quite sure where they are located but. That noise is the relay clicking on and off. They are actually pretty loud. Look for faulty connections to and from the relay and check battery power to both sides of the relay.

Try looking at the hot/cold switch.