auto repair question

Turned the heater on my truck this morning and most of the time it worked but occasionally it would stop blowing hot air. Couldn’t find any leaked fluids. Any ideas? Thanks in advance.

thermostat

What make, model, and year of truck?

Possible Low coolant level, does it go cold or stay warm when you lose the HOT heat.

More details would make it easier to help you out, feel free to call me 507-696-6722 Jeff .I am a fleet mechanic.

It’s a 2005 Ford Ranger 4×4 with the 4.0. It does go cold but will come back to hot after a little bit. Coolant level is good. Wouldn’t you smell coolant if the heating core was going. Thermostat was what I was going to start with but wasn’t sure. Thanks for the help.

Sounds like changing your Thermostat would best and cheapest start. Good luck and post back results.

Get it warmed upood running the heater.
If you’re not getting heat, open the hood and check the 2-hoses (In-flow & out-flow) going through the firewall. If the out-flow hose is cold you likely got blockage in the heater core.

If this is the case, wait for it to cool then pull the hoses off the firewall connections and Use a garden hose or Compressed air hose and blow water or air backwards through the heater core.

Then reverse and blow through in the other direction. If blocked, you should get some sludge to blow out.

I’ve had this done on a few vehicles.

If this is the problem and you get the sludge out, you should do a complete flush and fill of the Anti-freeze/coolant before winter.

Good luck.

I don’t think it’s the thermostat because the hose from the block is warm. I flushed the heater core this morning. The inlet hose is a little warmer the outlet hose, but the outlet hose is pretty warm. So is the heater core okay? I’m going to take it for a drive tonight. If the heater core was leaking could you pressure test it? Thanks Everyone

if it was leaking you would be loosing coolant, do you have to add it ever?

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if it was leaking you would be loosing coolant, do you have to add it ever?

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No, I opened the radiator cap and it’s full. Haven’t been smelling any coolant anywhere either. I’m hoping flushing the heater core worked. Thanks

not likely, but hopefully it did. more than likely the fins are plugged. I’ve had to take them out and clean them before, not a fun job. Hope that it doesn’t come to that.

I think the flush worked. I’m going to have the coolant changed next week. Thanks for all the help…I appreciate it.