Heater core or Thermostat?
10-21-2018, 11:39 AM
#1
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Heater core or Thermostat?
my 84 f150 isn't blowing hot air. The fan seems to work alright when I have it on defrost, but when I switch to heat it barley blows out any air let alone hot air. I'm not sure what the problem is as I think it might be my thermostat or heater core. I am just not sure how to tell the difference and know which one is giving me the problem. Any ideas? thanks
10-21-2018, 11:11 PM
#2
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If the t'stat was stuck open, the engine would never heat up fully; and you'd never get heat in defrost. Similarly: if the heater core is supplying heat for defrost, it can supply heat for all the other registers. If you get heat on any one setting, it's available for all settings.
But your description of the problem isn't clear... You said "on defrost", and then "switch to heat". Are you using defrost with the temperature set to cold?
But your description of the problem isn't clear... You said "on defrost", and then "switch to heat". Are you using defrost with the temperature set to cold?
10-22-2018, 07:10 AM
#3
Mark
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First... let’s see if you are getting hot coolant through the core. At engine operating temp.. select heat in the cab.. pop the hood and feel the 2 heater hoses that pass through the firewall .. both should been warm or hot to the touch. That will tell you... you have good flow through the heater core.