HVAC questions..lack of heat

[97exploder19]

Im trying to figure out my low/luke warm air temp situation. My heat will blow hot air but its not as hot as it should be, more like warm air. Im trying to narrow down the possible culprit.

I hear no clicking noise in the dash so I believe my blend door is working properly. I can get cold air to come out in the summer time.

There's another door that you can see if you take the glove box down, I believe its the fresh/recircuplating? Either way its closed until I turn the auto climate down all the way to 60 degrees then it opens. Is that correct?

I still need to check the heater control valve more thoroughly. The hose before the valve is hot, after the valve to the firewall, not too much. Does anyone know what position the valve is in with the engine off? Or can I manually push the rod on the valve to try and see if I get more heat? What about just bypassing the valve all together?

Im going to try the EATC diagnostic test today and see if any error codes get thrown.

If I flush the heater core with air pressure will I have any problems? Is the hose without the heater control valve the output? Just want to make sure im backwashing the heater core. It could be blocked up with **** due to its age.

Any other suggestions to look for?

 

[clevalley]

First thing I would check is for a thermostat stuck open. I know the hoses can 'feel' hot, but may not be hot enough.

I am not sure on the heater valve.

Air pressure on backwashing - I would start of with 20 psi but go no higher than 50 psi. It may be worth it to flush with a pressure flush bottle filled with acetone to ensure any gunk in there is blown out.

 

[97exploder19]

Thermostat was replaced last year with a new oem one. My temp gauge is consistently in the middle of the gauge.

 

[clevalley]

Did a bit of reading - if it is not the thermostat then next would think is the heater control valve, sounds easy enough to replace and makes sense - make sure you burp the system after doing so.

If I was going as far to replace it, I would go ahead and flush the cooling system before hand and forget about trying to backwash the heater core, but that is me.

http://www.explorerforum.com/forums/showthread.php?t=200863

 

[97exploder19]

Well I believe the heater control valve is working properly after checking it out today after work. The actuator rod goes back into the valve when I turn the hvac off and extends out when I turn auto mode back on. So, this leads me to believe that its just a dirty heater core. Im going to flush that out with the hose first and then take my compressor to it with a lower psi to make sure nothing is stuck in there.

Anyone know the heater core hose size off hand?

 

[corkey]

flush the core both ways,