Help! The heat in my car only works in the Afternoon????

This is very peculiar I know, but in the morning I turn the heat on – when the engine has warmed up – and only trickles of heat come blasting out riding on cool air. WTF?? It’s like lucwarm air only in the morning. When I get in the car in the afternoon the air is pretty much warm to hot. Maybe it’s not as hot as it should be and I am only used to the lucwarmness??

Any body have an idea as to why this is happening?

I have a 98 Rav-4. In great condition…except the heater. :confused:

When the Rocketeer-o-van was having feeble heater output, I finally ended up flushing the heater core. I looked at the hoses a bit and figured out which was the inlet to the core, then disconnected both hoses and ran water into the outlet (that is, the water flow was reversed from its normal direction). Big clump of gook came out the open inlet port; heater’s worked fine ever since.

Same thing happened on my Dad’s old Valiant.

Another even simpler possiblity.

Make sure your coolant system is full. As they get low, the first place that is deprived of water is the heater core (in most cars).

So, ususally the first symptom of low coolant is poor heater performance.

And if that doesn’t do it, take a look at the thermostat. Although, if the thermostat isn’t working, you shouldn’t be getting warm air at all, it’s still a possibility. I’m betting on the low coolant level…

All three suggestions above are valid possibilities. In general terms:

Poor coolant flow through the heater due to a restriction
Poor coolant flow due to low coolant level
Not much heat in the coolant due to faulty thermostat

Any of these conditions can result in very little heat actually getting into the heater core. I would guess that it feels warmer in the afternoon because the outside air temperature is warmer. With a fully operational heater, the output air would be hot enough that you wouldn’t notice the difference.

Again! The Teeming Millions have done it. A thousand thank you’s to all who responded with the coolant level.

I went out and checked the level and it was very low. I filled it and tried the heater and its blasting nice hot air!!! I am sure it will work in the morning as the air is hotter than it’s been ever!! Thanks again!!

You’re welcome.