[svtboy]

I have a 1994 SVT and for the past couple of days i have noticed that when i have the heater on in my car the temperature of the air coming out of the vents fluctuates. Usually i have no problems keeping warm in my car. It is usually way more than hot enough for me.
But for the past few days the air coming out of the vents is barely luke warm and randomly it will get to its usual heat level for like ten seconds then go back to being luke warm.

So my question is What could cause this?

The car's water temp is at the normal 210 degrees and doesnt fluctuate at all really. also, when i turn the climate control to the cold side the air does get colder but when i go back to hot it only gets luke warm

[STINGREY]

could be a clogged heater core,bad thermostat, faulty control valve.needs to be checked out.

[spdjnky_42]

Sounds like a stuck/broke door

[cliff45890]

Either stat or heater core. Change or remove the stat first and run the car until operating temp to troubleshoot. If you get heat than you know it was not your heater core. The door is run off a vaccume. You will hear it open and close when you toggle your switches.

[8MSBHVN]

It could be a vaccuum leak. The line goes from the middle of the firewall over to the driver's side fender. This hard plastic line is for the vaccuum door. I've had mine leak twice now. A bad connection could cause the fluctuation you're describing.