Running rough with heat on

[StreetKill831]

So it's winter now and here in MI having heat is a must. Lately I have been having to go without heat because when I drive with the heat on the engine seems to run rough. I can somewhat hear it but mostly I feel it in the floor and pedal.

Oil is good and fresh and I recently flushed the radiator and filled with Toyota Red. Anyone know what could be going on?

Thanks,
Brian

 

[SP Jon M3]

Are you running just heat? or are you running defrost? If you're running defrost then it's linked to the AC. Meaning the AC turns on with the heat to remove the moisture from the air thus keeping your windows from fogging up.

You can check to see if it's the AC causing the problem, just turn your AC on and see if it runs the same as when you turn your heat on.

 

[StreetKill831]

I have been running it w/o AC because currently my AC switch is broken, it doesn't click in.

 

[brian2sun]

Defrost automatically kicks the A/C on whether you push the A/C switch or not. Try moving the selector to just the vents and/or floor and see if it runs better.

 

[StreetKill831]

It runs rough on all settings. BTW I didn't say before, but this is on my '98. Other than the 99yrs+ being digital I don't think it makes a difference though.

 

[SP Jon M3]

Even the non-digital systems had the AC kick on when you select defrost for the front window. At least that's the way it worked in both my Tacomas.

 

[StreetKill831]

Anyone know what could be going on?

 

[SP Jon M3]

Well, the problem is the heating system is real simple. When you turn the heater on, air passes in front of a small radiator in the cab. There's no mechanical or engine reliant system for just the heater. The only thing that I would think would make a difference in the engine operating would be if the ac kicked in, which is why I asked if it you were using the defrost. Maybe your low on coolant? but even that I don't see as causing the engine run rough, and even more so I would think that it would run rough no matter weather the heater was on or off..

Have you tried just turning on the ac? Does it cause the same problem as when you trun just the heater on?

 

[004Gunner]

Is the problem effected by fan speed?

 

[StreetKill831]

I'll have to get someone to ride with me and hold down the AC button since it's broken but we'll see if it does the same thing. I don't think fan speed makes a difference.