1993 Deville has no heat!

Northstar engine. You can put the climate control on 90 or 60 and it still blows the same temperature. MOST of the time, its cold air. Although, I did let it sit and run for about 30 minutes one time and came back and it was the opposite, no matter what the temperature was on, 60 or 90, it blew warm air. Has a new water pump. Both radiator hoses are hot. One heater hose going to the heater core is around 170-180 degress and the other is about 140-150. A/C Compressor kicks on sometimes and sometimes is don't. I am clueless? HVAC Control Head? Blend/Mixing Door? I figure its not the thermostat since both hoses are hot. I tried tapping the thermostat housing to make sure it aint stuck and it didn't change anything? Since both heater hoses were RELEVENTLY close in temperature, I ruled out the heater core also. I want to think its the control head since it works a FEW times but not all the time? Any help or diagnostic tips/procedures would be greatly appreciated. Thanks!

I don't know about your specific car, but it your heater core could be clogged. Since both radiator hoses get hot you can rule out the thermostat because coolant it flowing through the engine, but that doesn't mean it is flowing through the heater core.

There should be 2 smaller coolant hoses (heater hoses) going to the firewall and if those are both getting hot with the heat turned on and up then your heater core isn't clogged.
There is probably a vacuum actuated valve on one of them that opens to allow coolant through. You could see if it opens freely by hand and make sure it isn't disconnected somewhere.

Dustin

id try and hit a junk yard and take the ecc (electronic climate control) unit off another car i had this same problem on mine the only thing was before i got a new radiator i put in a bunch of stop leak in the coolant system and it clogged my heator core im still trying to get it all out and this was like 6 months ago, just hook a hose up to the heater core lines and turn the hose on simple.

What are the odds the heater control valve is bad? I pulled all the heater hoses off of it and two of the ends were broke but I don't think that would affect it since its just the ends. I looked up info about the blend/mix door on ShopKey5.com and it only had info about testing the blending door, but not about removal/installation? So I don't know if you can replace just the door/actuator or if you have to replace the whole duct section or something? I really don't want to buy an ECC and that not be it. Is there anyway to test the ECC? What about the thermostat being stuck in the open position? Any possibility of those?

ok the ecc unit controls a lot more than just the climate this is like a diagnostic reading system for the car too, its gonna be expensive brand new but, when i took my car to the mechanic he said to get to the heater core, blower motor or anything like that is fairly easy compared to most cars and ya the thermostat could be stuck thatd be an easy check try that and also, and one more thing that heater valve was broke on mine too i replaced that with just a basic pvc T and flushed the heater core and that fixed my problem, try that if these arent the problem try the ecc unit from a junkyard, there its only gonna be like 10 or 15 bucks

Obviously Cadi509 knows more about the system that I do. Like I said I don't know about your specific car. Just thought I would throw a suggestion out there.
I had a car that the vacuum line for the heater control valve would mysteriously pull out on occasion. It is something easy and free to check. I'd hate for you to replace a bunch of parts just to find a broken vacuum line.

Dustin