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Old 12-06-2020, 01:51 PM   #1
Starwood
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Blower and A/C fine - but No Heat?

Fuse is good, and AC is pouring ice cubes out the dash when needed.
I do have aftermarket switches that control temp and 3 blower speeds, but when I turn knob to right for heat - nothin but cab temp air flow.

Stumped....

Here are a couple pics of the setup. Any ideas?
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Old 12-06-2020, 02:55 PM   #2
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Re: Blower and A/C fine - but No Heat?

Coolant level correct?

Operational thermostat?
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Old 12-06-2020, 03:11 PM   #3
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Coolant level correct?

Operational thermostat?
Yup. New Crate engine and a new thermostat went in. Coolant topped. Grrrr....
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Old 12-06-2020, 03:15 PM   #4
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Re: Blower and A/C fine - but No Heat?

If you feel the heater core lines, are they hot? Is there an inline valve to stop coolant flow to the heater core? Is there a door in the heater box to switch between heat and AC? You may need to open it up and verify it is moving. I had a door come disconnected from the shaft, so the shaft would spin, but the door wouldn't move.
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Old 12-06-2020, 06:45 PM   #5
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Re: Blower and A/C fine - but No Heat?

Looks like there is an in-line vacuum operated heat valve in the heater hose. Maybe it is closed and no vacuum. An in-line mechanical valve would be simple to install and an easy control for on/off heater core coolant flow.
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Old 12-11-2020, 03:52 PM   #6
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Re: Blower and A/C fine - but No Heat?

Thanks for the follow up.

I suspect it may be a clogged heater core, and I'm going that route first.
Per pic above and new attached - my core is inside the cab, and a flush from inside seems like a messy gig that might ruin some carpet if I'm not careful.

Question: Can I get decent results doing a reverse flush using the external hoses?
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Old 12-11-2020, 04:55 PM   #7
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Re: Blower and A/C fine - but No Heat?

Yes. You can flush the core from the engine side. Start with the return hose (the larger diameter). Then flush it the other way. I have a hunch the problem is in the vacuum controlled valve on top of the blower.
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Old 12-11-2020, 08:48 PM   #8
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Re: Blower and A/C fine - but No Heat?

Quote:
Originally Posted by Wrenchbender Ret View Post
Yes. You can flush the core from the engine side. Start with the return hose (the larger diameter). Then flush it the other way. I have a hunch the problem is in the vacuum controlled valve on top of the blower.
George
You're probably right, but I'm thinkin the flush is probably gonna help down road anyway!
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Old 12-12-2020, 02:24 PM   #9
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Re: Blower and A/C fine - but No Heat?

Quote:
Originally Posted by Wrenchbender Ret View Post
Yes. You can flush the core from the engine side. Start with the return hose (the larger diameter). Then flush it the other way. I have a hunch the problem is in the vacuum controlled valve on top of the blower.
George
Thinking more on this - good point, Wrenchbender. If I'm going to reverse flush, might as well thrown in a new $15 valve while I'm at it. Guess that puts me back in the cab for the job. I'll lay down some plastic and protect the carpet as best I can - wish me luck...
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Old 12-12-2020, 02:48 PM   #10
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Re: Blower and A/C fine - but No Heat?

On your heater valve, do you have a bypass heater valve (as an example) like this? That allows the coolant to return to the water pump from the intake when it is off?
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Old 12-12-2020, 09:06 PM   #11
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On your heater valve, do you have a bypass heater valve (as an example) like this? That allows the coolant to return to the water pump from the intake when it is off?
Hey Rocknrod - the valve is inline and theres a pic above. Thx
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Old 12-13-2020, 07:18 AM   #12
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Re: Blower and A/C fine - but No Heat?

If it were me I'd test that it opens and closes but you'd need to drain the lines to "see" it. But that's just me.
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Old 12-14-2020, 04:44 PM   #13
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Re: Blower and A/C fine - but No Heat?

Quote:
Originally Posted by Wrenchbender Ret View Post
Yes. You can flush the core from the engine side. Start with the return hose (the larger diameter). Then flush it the other way. I have a hunch the problem is in the vacuum controlled valve on top of the blower.
George
So - just to be clear: Remove the large diameter hose on intake and flush that direction. The flow then should be coming out of the hose attached to the water pump, correct?
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Old 12-14-2020, 05:59 PM   #14
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Re: Blower and A/C fine - but No Heat?

Wrong! The large hose is on the water pump. That is the return line. Disconnect the hose from the intake man. & flush from the return line to the inlet line. That will reverse flush it. After that flows good you can flush it the other way if you want.
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Old 12-15-2020, 03:55 PM   #15
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Re: Blower and A/C fine - but No Heat?

Welp...that was FUN.

Decided to flush from inside and the hose attached to one inlet was stuck on like a mutha. Promptly snapped the intake to the core and now it not only needs a new core, but I can't even find anything related to the part number.

Days like this make me want me to sell it to a buyer the first $10, but I'd feel guilty. This truck has nothing but bad luck since day 1.

Anyway, gonna bypass the heat and AC until I can find replacement - or have the $$ to send out to a shop and just take my lumps. Whatta major drag.
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Old 12-15-2020, 07:13 PM   #16
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Re: Blower and A/C fine - but No Heat?

The first pic almost looks like the unit Restomod Air uses.
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Old 12-20-2020, 04:16 PM   #17
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Re: Blower and A/C fine - but No Heat?

Turns out this is an AC/Heater evaporator combo.
These units can be pricey! And that's even you find one.
I'm going to see if I can have the inlet reattached by a Pro.

Question: I'll obviously need to disconnect to AC lines to get the unit to a shop. Is it OK to simply disconnect the AC lines - or am I at risk for screwing this up further?

I'm aware I'll need a system recharge after repair or replace, but don't want to damage other components - or get even deeper into what was a minor heating issue.

Thanks in advance for any thoughts on this.
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Old 12-30-2020, 02:14 PM   #18
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Re: Blower and A/C fine - but No Heat?

Is it OK to keep my Compressor on the belt while I've bypassed the AC/Heating system?

Also, if anyone knows where a guy can get evaporator kit parts, please send me a PM. Most are sold as kits and come with wayyy more than I need.

Thx Fellas.
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