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Changing heater control valve.

darrenwgaransi+
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Changing heater control valve.

Postby darrenwgaransi+ » Sat Jan 12, 2019 4:26 pm

Hi Everyone. How hard is it to change the heater control valve? It’s freezing here in the northeast and I’ve had enough of mediocre heat. I’d like to figure out how to unscrew it from the engine block without cutting up my hands. It looks hard to get to.
Darren W. Garansi
1993 XJ6, 4.0

Brake buster
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Re: Changing heater control valve.

Postby Brake buster » Sat Jan 12, 2019 5:39 pm

very hard to get to in reality

removing the wiper scuttle motor mounting will improve things, but that is a job in its self if its stuck

have you tried manually opening the valve so the heat flows all the time

this setting is the default, and when the vacuum is applied it shuts the valve to allow cold air in the cabin

BB
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naki_k
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Re: Changing heater control valve.

Postby naki_k » Sat Jan 12, 2019 6:54 pm

Brake buster wrote:very hard to get to in reality

removing the wiper scuttle motor mounting will improve things, but that is a job in its self if its stuck

have you tried manually opening the valve so the heat flows all the time

this setting is the default, and when the vacuum is applied it shuts the valve to allow cold air in the cabin

BB


As mentioned. Fully open is the default position.
So when the valve fails is does not stop heated coolant entering the matrix.
The valves job is to close off the flow for summer time.
Are both fans working on all blowing speeds? It’s more likely your blower motors/ fans are giving up and not actually blowing hot air.
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darrenwgaransi+
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Re: Changing heater control valve.

Postby darrenwgaransi+ » Sat Jan 12, 2019 11:22 pm

Hi Everyone,

I manually operated the valve. It is operating normally, even though there’s a very slight leak. The fans are working fine. The both blow air at all speeds. Engine temperature is right in the middle. The air coming from the lower vents just isn’t warm enough and there’s not much of it, even though the motors are working. Most air actually comes from the rear vents for the back seat. Everything is fine with the air conditioning. I wonder if it’s the heater/ac blend door?
Darren W. Garansi
1993 XJ6, 4.0

naki_k
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Re: Changing heater control valve.

Postby naki_k » Wed Jan 16, 2019 1:20 pm

darrenwgaransi+ wrote:Hi Everyone,

I manually operated the valve. It is operating normally, even though there’s a very slight leak. The fans are working fine. The both blow air at all speeds. Engine temperature is right in the middle. The air coming from the lower vents just isn’t warm enough and there’s not much of it, even though the motors are working. Most air actually comes from the rear vents for the back seat. Everything is fine with the air conditioning. I wonder if it’s the heater/ac blend door?


Process of elimination then. So it’s likely the blend flaps or the ECU/ sensors controlling them.
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 4.0 XJ6 Manual
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94 4.0 Daimler
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2000 LR Discovery ES TD5 A
Breaking 40/ 300

darrenwgaransi+
Posts: 73
Joined: Thu Nov 24, 2016 5:58 am
Location: Hamilton Square, New Jersey
Contact:

Re: Changing heater control valve.

Postby darrenwgaransi+ » Thu Jan 24, 2019 2:40 am

I don't really know what to make of this problem. The lines going in and out of the heater core are very hot; therefore the coolant flow is adequate. The servos are responding correctly to output from the climate control module and moving the blend cylinders, yet the air coming from the heat ducts just doesn't seem hot enough when it is below freezing outside. Is this a design thing? I can turn the heat all the way to hot, switch from auto to manual and still there's a limit to how hot the air becomes. The output is nowhere near to the temperature of the heat in my Toyota Tacoma.
Darren W. Garansi
1993 XJ6, 4.0

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Re: Changing heater control valve.

Postby pimgmx » Thu Jan 24, 2019 8:50 am

Clogged heater matrix?

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katar83
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Re: Changing heater control valve.

Postby katar83 » Thu Jan 24, 2019 10:26 am

pimgmx wrote:Clogged heater matrix?


+1

Apparently this can be removed without disassembling half of the car but I'm not sure how that would be possible.

Maybe it would be possible to flush it with one end connected to pressured water source? Or maybe lift up front of the car and fill it up with some descaler, etc? :) Removing dash sounds like a daunting task so I'd probably try all other things first.
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