2002 GMC Yukon XL 1500 front heater is blowing cold air but rear heater is blowing hot air

You probably should have a look at the video! Good luck with it!

Ok will do n ill keep u posted if it worked. Thanks

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I tried it n it didnt work. I got heat with fan at low to medium speed but once i set to high speed it starts blowin cold air again

Also as the car is running i would rev engine up to 2 on rpm meter n it would get warmer but as soon as i let go of gas pedal it would start blowing cold again. Any new suggestions?

Recheck coolant level and make SURE it’s *FULL* .. It sure seems to me like a restricted heater core - with fan on lower speeds - it doesn’t cool the core off as much as on higher speeds .. Revving the engine also increases coolant flow through the core .. Feel both heater hoses again - with engine at operating temperature - BOTH heater hoses should be as HOT as the upper radiator hose is! ... You shouldn’t be able to hold on to them for very long without it becoming uncomfortably warm.. It is a coolant flow restriction OR the temperature bafflle still isn’t working correctly .. That is the only logical conclusion. IF water pump or thermostat were not operating properly - engine *temperature gauge* would indicate that! ... Would see either engine overheating (pump) or running too cool (t-stat). Now you may very well have either of those symptoms present .. I have no way of knowing..

Ok will try that. Again thanks for your help n suggestions

‘IF’ there is a *heater control valve* present in the heater hoses (?) - that also needs to be tested. Again > Good luck with it!

Ok will check for that too. First im going to flush my heater core cause when i felt the hose they were hot but i was able to hold them. Thanks