2000 f150 heater only got warm.
Flushed system, new thermostat, new coolant. Then NO warm air.
A/C blows cold. Checked heater blend door and actuator both intact and working.
Heater core not leaking, system holds pressure and doesn't leak.




Is there another automatic valve that could be shutting off flow to heater core?????

 

Only if added after it left the factory. Did you think to look for any such thing in the coolant loop?

Did you bother to check the heater core inlet and outlet lines to see if there is hot coolant circulating through the loop? No hot coolant = no heat.

Causes of no coolant flow: Low on coolant, air pocket, restriction ion the loop, worn out (eroded) or broken water pump impeller, thermostat stuck open or otherwise bypassed.

 

That I was what I was going to try this weekend. I verified flow to firewall of hot coolant. Having a hard time reaching heater core outlet hose to disconnect. Older man


Coolant level full, new thermostat, engine temp gauge shows cool on startup then needle rises to normal temp as you'd expect. I squeezed upper heater hose to see if bubbles came up to reservoir tank...didn't see any. Water pump I have not ruled out but truck doesn't overheat.....hum?


I've put more flush and planned on running it through system for a few days before it gets cold.


Thanks for your reply. I know it's an old truck but the last time I had to work on my own vehicles was in the 70's and things were a LOT less complicated.

 

No need to disconnect it, just touch it (very gingerly!). You'll know if it's hot or not real fast.

it is not uncommon for these trucks to NOT overheat with a failed water pump.

 

Thank you. I'll look at it again this evening. Feel of the heater core hoses...gingerly.


I'd rather it be the water pump. As hard as it would be to change out, it's still looks easier than what Chilton shows for the heater core.

 

Yeah, the whole dash has to come out for a heater core. A whole day job, if you're lucky.

 

So... how is this coming out? My 99 only blows luke warm air. Touching the hoses, I can't tell if there's water in 'em or not. One thing I do note is that on one of the hoses there's a "something" held in place in the line. Wondering if that's a blockage point? I'm thinking of cutting it out just to see what it is, since I can't find it in Chiltons. It's a factory gizmo in the line, held in place with factory crimped clamp. No idea what it's for, unless it's to stop back flow.

I also flushed my system, but the whole reason for it, was because of no heat.

If there's air in the line, would a "flush kit" take care of that issue? I plan on putting a flush kit fitting in the line and seeing if I can force some air through the heater core to make sure it isn't plugged. ( I have been a slacker on changing antifreeze regularly! But a lot of my woes are caused by some chitty life situations and living on Social Security retirement income. Makes being able to afford proper maintenance an flippin' issue. But...'nuff whining. I need to get some heat pretty sudden like. WIll work on things a bit tomorrow, since there's a lack of in-coming snow for a while.

In any case... with temps getting way into the MINUS numbers, I'm starting to get desperate to fix my baby. She only has a touch over 150,000 miles and hate the thought of having a shop do the stuff I ought to be doing. I'll stop by in a day or so to see what's up. Dang snow plowing is keeping me busier than a man my tender age ought to be.