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Discussion Starter · #1 ·
Hi guys,

I have been driving my car a little bit here and there, and noticed that my heater only blows cold air. I'm wondering if I hooked up the inlet and outlet lines backwards at the engine and it is not cycling water through the heater core. Anyone know if the heater is a one way system, or if it could be a stuck valve somewhere?

Thanks for any help as always,

You all have been a great help in getting my car running well.
 

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anyone have some insight on a heater that only puts out cold

If memory serves me right there is a heater tap on the nearside chassis leg under the bonnet. Early shadow 2 were at front near bottom hose connections, later cars were under brake fluid tank. If you remove the plastic cover, disconnect the cable, you can manually turn valve and see if that gives you heat. if so then you know valve is ok. If you get someone to work heating controls you can also check if cable is moving. Cable is connected to where acu servo motors are behind carpet below centre console on dash. Hope that is some help
 

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Discussion Starter · #3 ·
When I got home I played with the switches and noticed that the cutoff valve for the heater lines wasn't moving. Swiched it to warm and helped it along and voila. It started working . I guess it got stuck from sitting the last decade, but not the valve itself, but the little actuator that controls it. Now the heater is warmer but not hot. I'm wondering if there is something else the matter. I hope it's something simple as I don't want to take the dash apart for this
 

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When was the thermostat last changed? If these fail in the open position (and they typically do, thank heavens) it will take a much longer time than you'd expect for the engine to heat up to the point where the coolant flowing through your heater core would be hot enough to produce "hot".

The amount of travel on the heater tap is quite extensive and, if you have the old style, they can fail partially internally and not ever give full flow.

Also remember that these systems are set up so that if the ambient air temperature is above freezing they will cool all incoming air (to remove humidity) before heating it again.

Just as a general matter, it always makes life easier for those of us trying to answer these questions to have the model year and chassis number of your car.
 

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Discussion Starter · #5 ·
Sorry, the chassis is LRE23822 1976 shadow LWB it is a transition model which still has the full center console type dash, but has the heater coolant valve actuated under the brake fluid reservoir. The thermostat was working properly when the engine was installed, and the radiator hoses are burning hot so the engine is up to temp. I hear movement every time i turn a switch, but the heater only has a slight warmth to it. I live in California, so the temp here when i tried it was about 65F. I will see in the morning as temps drop down to 40-50degrees . I haven't opened the heater box but might give that a try as a last resort
 

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I very much doubt that it is the heater core at fault here. When they fail you typically end up with coolant leaks and you know it relatively quickly.

My guess is that this issue is going to end up being traced to issues with your actuators for the mixing flaps, the bushings (plastic, old, fragile, and likely fractured/broken) for the mixing flaps, or both.

Regardless of which it is, you will have to tear quite a bit apart on the dash and center console to gain access to either.

You could also have a problem with the main air conditioning/heat control unit (one was recently up on eBay that didn't sell and was listed by a member of the Rolls-Royce Owners' Club who bought it at the Bentley Heritage Parts Tour).

Also, do not discount that these systems try to keep the cabin comfortably warm or cool and seldom blast really high heat unless the outside ambient temperature is cold. When it's actually warm outside turning the system on and the dials to full warm just causes the system to shut off, not roast you out.
 

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Discussion Starter · #7 ·
I think I just confirmed the mixing flaps are not working. It was 35F outside and the heater was nice and cold. I will take the engine bay housing apart first as I have to do some work in there, after which it's on to the dash. Fingers crossed for a simple fix, but it seldom is.

Thanks for the help
 

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anyone have some insight on a heater that only puts out cold

If you look at the front of heater box in the engine compartment there is a box on it with 2 actuators. If you remove the cover, self tapping screws hold it on, you will find 2 rods that work the heater flaps. again if you disconnect you can see if flaps are loose/working. It is probably a case of the bushes have worn. Not to bad a job to do you can access them my removing heater box under bonnet. A fair amount of work but not as bad as first seems. hope this is some help
 

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I also have the same issue with my car, its a 76 LWB. The thermostat and control valve seem ok, so maybe its the flap issue too. I live in PA so the car doesn't come out too often in winter, but when we get a break of nice weather I'd like to get it out, but need a little heat!
 

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Discussion Starter · #10 ·
well i got lucky. It turned out to be a bad heater core valve. mine was stuck at first and upon release i found it to be ripped. I fixed it for about $15 (made my own diaphragm ) and all is working perfectly now. you guys are right about the controlled temperature, as it comes out hot at first to warm the car after which it levels out and keeps a comfortable 70+ degrees F. All is well now and i did check all my linkages and everything is in pristine condition.

on the heater side the only flap that does not function for me is the one right above the radio which is supposed to be manual. it is frozen solid and someone removed the handle to move it. I'm assuming it was removed as the 2 screws holding it in are gone also. either way, i was not able to get it open even with a bit of force. i will get to it eventually but for now i'm happy with my findings.

thanks for all the help once again. it seems most of my problems are due to the cars long rest untouched.
 
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