940 '93 heater valve removed

malloy1 · 06-21-2012, 07:46 PM

The PO took out the heater valve that is on the engine side (vacuum line is plugged). I'm going to be replacing all the coolant hoses (including the heater hoses), and now wonder if I should install the new heater valve I bought. The AC seems to blow cold, and the heater seems to work fine. What is the use of this heater valve if there is another valve somewhere else that controls the coolant to the heater core? Will the AC be colder?

Paul

Magnum TE · 06-21-2012, 08:21 PM

The purpose of that valve is to shut off flow to the Heater Core when you have the MAX AC setting selected (that little click at the bottom of the temp dial). The AC will blow cooler. The side effect of this is that it stops flow to that back part of the head when the valve is closed.

I am using a GM heater control valve that Gary suggested. It's a 4 port valve and allows flow through the head when the heater core flow is closed.

7/9 Updated Heater Control Valve

That being said, no harm will come from not having that valve.

Clay · 06-21-2012, 08:23 PM

I haven't had a valve in my 940 for 3 years.

gsellstr · 06-22-2012, 12:35 AM

Actually Toby, having flow thru the valve when not intended will cause a noticeable loss in performance from the AC system. The air is getting heated by a hot core just before it gets cooled. Found about a 10* difference from a partially stuck open heater valve to a sealed closed heater valve.

The 7/9 series use a blend door system for temp control, which means once you just barely move the lever off the cold side, the valve opens and coolant flows thru the core, with a door controlling the temp. Not quite like the old 240's with a valve that controls the temp.

malloy1 · 06-22-2012, 10:00 PM

Replaced all the coolant hoses and the heater valve.

Replaced the heater valve with a new Motorcraft one (which I had), but really like that two hose GM valve. I would use the GM one next time (but I figure I have 50K or 100K before I need to change that one again).

Thanks-

Magnum TE · 06-22-2012, 10:31 PM

Quote:

Originally Posted by gsellstr

Found about a 10* difference from a partially stuck open heater valve to a sealed closed heater valve.
.

LOL my AC doesn't cool more than 10deg under ambiant temp anyhow, so I've got no frame of reference.

Clay · 06-22-2012, 10:36 PM

Quote:

Originally Posted by gsellstr

Actually Toby, having flow thru the valve when not intended will cause a noticeable loss in performance from the AC system. The air is getting heated by a hot core just before it gets cooled. Found about a 10* difference from a partially stuck open heater valve to a sealed closed heater valve.

The 7/9 series use a blend door system for temp control, which means once you just barely move the lever off the cold side, the valve opens and coolant flows thru the core, with a door controlling the temp. Not quite like the old 240's with a valve that controls the temp.

The air conditioning in my 940 blows between 38-42 degrees when I'm moving. All original air conditioning.

andysbeta · 06-22-2012, 10:37 PM

Yeah running without a heater valve won't hurt anything but indeed the A/C won't be as efficient without one as I've too experienced about the same difference in vent temps without vs. with.

50 degree dash vent temps are okay with the heater valve missing, but if you get a drop of 10 degrees to say 40 degrees at the dash vents, then that is getting pretty darned good and nice cold A/C indeed.

Clay · 06-22-2012, 10:49 PM

Quote:

Originally Posted by andysbeta

Yeah running without a heater valve won't hurt anything but indeed the A/C won't be as efficient without one as I've too experienced about the same difference in vent temps without vs. with.

50 degree dash vent temps are okay with the heater valve missing, but if you get a drop of 10 degrees to say 40 degrees at the dash vents, then that is getting pretty darned good and nice cold A/C indeed.

That's what I run with the heater valve bypassed.

06-21-2012, 07:46 PM	#1
malloy1 Board Member Join Date: Nov 2003 Location: Denver CO	'93 heater valve removed The PO took out the heater valve that is on the engine side (vacuum line is plugged). I'm going to be replacing all the coolant hoses (including the heater hoses), and now wonder if I should install the new heater valve I bought. The AC seems to blow cold, and the heater seems to work fine. What is the use of this heater valve if there is another valve somewhere else that controls the coolant to the heater core? Will the AC be colder? Paul __________________ Paul

06-21-2012, 08:21 PM	#2
Magnum TE Broke another B230F+T Join Date: Nov 2002 Location: Santa Rosa Ca	The purpose of that valve is to shut off flow to the Heater Core when you have the MAX AC setting selected (that little click at the bottom of the temp dial). The AC will blow cooler. The side effect of this is that it stops flow to that back part of the head when the valve is closed. I am using a GM heater control valve that Gary suggested. It's a 4 port valve and allows flow through the head when the heater core flow is closed. 7/9 Updated Heater Control Valve That being said, no harm will come from not having that valve. __________________ Goldie Bricks - '92 940T : B230F+T MSnS-e... The Gray Car - '92 940T : stock drive-train DD I have some cool stuff done to my cars The Gold Car: Owner since 2001 B230F+T MS1nS-E / Ford T5, 1pc DL ebay FMIC / Mechman Alternator T3 60/.63 ATP WG / 63#/hr CFI injectors Full 3" Turbo to tail / IPD TP Cam IPD bars / Coilovers Koni Dampners / Lower Chassis brace NIW-T3 camber plates / Full poly front end Full Kaplhenke Rear end -Torque rods -PH Bar -Subframe Daily Driver Last edited by Magnum TE; 06-21-2012 at 08:40 PM..

06-22-2012, 12:35 AM	#4
gsellstr Vintage anti-ricer Join Date: Oct 2004 Location: Somewhere in a northern California smog bank	Actually Toby, having flow thru the valve when not intended will cause a noticeable loss in performance from the AC system. The air is getting heated by a hot core just before it gets cooled. Found about a 10* difference from a partially stuck open heater valve to a sealed closed heater valve. The 7/9 series use a blend door system for temp control, which means once you just barely move the lever off the cold side, the valve opens and coolant flows thru the core, with a door controlling the temp. Not quite like the old 240's with a valve that controls the temp. __________________ RIP Doug "Mr. Doug" Williams, 4/15/2009 74 144 B20 http://forums.turbobricks.com/showthread.php?t=224983 90 745Ti, AW71L, IPD bars/springs, Koni SA's, JVAB B230FT, Big Valved 531 head, IPD Turbo cam, GT2871R @ 18psi, TLAO chips, E85, NPR, 3.5" DP, 3" DP-back, MSD, TruTrac, Wilwood BBK If you need Superpro bushings PM me or check the current GB, running until 3/31/13 at http://forums.turbobricks.com/showthread.php?p=4493644).

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06-22-2012, 10:00 PM	#5
malloy1 Board Member Join Date: Nov 2003 Location: Denver CO	Replaced all the coolant hoses and the heater valve. Replaced the heater valve with a new Motorcraft one (which I had), but really like that two hose GM valve. I would use the GM one next time (but I figure I have 50K or 100K before I need to change that one again). Thanks-

06-22-2012, 10:37 PM	#8
andysbeta no point Join Date: Jun 2003 Location: Mancos	Yeah running without a heater valve won't hurt anything but indeed the A/C won't be as efficient without one as I've too experienced about the same difference in vent temps without vs. with. 50 degree dash vent temps are okay with the heater valve missing, but if you get a drop of 10 degrees to say 40 degrees at the dash vents, then that is getting pretty darned good and nice cold A/C indeed.