Jim Grant's Tech Tips
95 Chevy Tahoe, Heater Blowing Cold Air
My ‘95 Chevy Tahoe was serviced for a manifold gasket leak and now my heater blows cold air. I have replaced the thermostat and had a tech verify that hot water is in the heater core. Every once in a while after stop and go driving I will start to feel warm air but it will stop after 45 seconds and go back to cold air. Please help! I am low on funds and would like to fix it myself if at all possible.
- Anthony Pena
We had a problem similar to yours in the shop a while back. The engine had been repaired at another shop. Since the repair, the heater would blow hot air erratically at best. To make a long story short when the heater core was back-flushed, part of a shop towel flushed out. It is a common practice to use a paper towels, shop towels or shop rags to block/cover passages in the engine while cleaning, (scraping or grinding) parts of the engine while it is apart in the vehicle. Once in a while, a tech will forget to remove said product or part of it remains in a passage. Reassemble; fill it with fluids and start the engine and you can only guess where the leftovers end up. Try a back flush own your heater core. You may be surprised what might flush out.