1991 Ford F-150 no hot air in CAB

TC1912

MEMBER
1991 FORD F-150

Heater problem
1991 Ford F150 6 cyl Two Wheel Drive Automatic 130K miles

Hi, replaced heater hoses, blew out heater core (appears no obstruction). Water pump is new 6 months ago, as is thermostat and housing. 4.9L, E40D transmission. When engine reaches operating temp, the hose to the thermostat is hot, hose to the pump is cold! Again the core looks brand new and was easy to blow fluid by mouth through it. Still no luck with heat. The temp lever in cab has very little affect in bringing warmer air.

Hmm,

Thank you

3 Replies

BLACKOP555

MECHANIC
10,371 POSTS

What hoses are not hot? Can you get a picture and circle the hoses that are cold and hot? You may need a cooling system flush.

Do the heater core hoses get hot?

Why was the water pump replaced?

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Saturday, December 20th, 2008 AT 12:47 PM

TC1912

MEMBER
1 POST

Water pump was replaced due to leaking, also thermostat and thermostat housing were replaced due to corrosion.

Both hoses get hot now. Both didn't get hot until I put some drive time on the vehicle. It appears now that when I use air conditioning then go to heat, the heat takes up to a minute or 2 to become functional. I believe this is an intermittent issue. I will keep testing and let you know the results.

Thank you

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Saturday, December 20th, 2008 AT 7:07 PM

BLACKOP555

MECHANIC
10,371 POSTS

Alright get to me with the results. Always keep your eye on the temperature of the heater core hoses, can tell us weather its blend door related or cooling system related.

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Sunday, December 21st, 2008 AT 7:42 AM