Heater control valve

bjtstarfire · 12-14-2006, 04:59 PM

What is the best way to check the operation of a HCV on a 61 Olds (It is vac. operated) or the heater t-stat?

Should I just connect the vac line from the HCV that goes to the t-stat directly to a vac source?

Is the valve normally closed then opened when vac is applied?

Some background: Heater core is not blocked, water pump is good, coolent level is correct, hoses are fine, no air bubble. When the heater is on the fan blows cool air so the blower motor is functioning and the vac that controls the master blower switch mounted on the heater core blower housing, inside the engine bay, is good.

Ben

Happy Holidays and Motoring (When me and my daughter go for rides looking at the Christmas lights it gets pretty cold - she needs a blanket due to no heat).

Oldsguy · 12-15-2006, 05:10 AM

sounds like you are going to do it right, another way to gaurantee that water is flowing through the core is to simply leave the return hose to the control valve open and let it dump down the side of the engine in the front of the firewall. I would think that as soon as you start the engine the water will start flowing as the water pump is not clutch operated, you should only have to let it dump for a few seconds. Of course the water would still be cool but that would verify circulation to the valve inlet AT LEAST. Then you can also, try running it w/o the valve. After the engine heats up you should have HOT air through your vents unless there is some other problem. That's my two cents anyway.

ozoneblue · 12-15-2006, 07:38 AM

Try installing a flush T in the return hose unscrew cap to bleed system.Also make shure you have a good radiator cap so the system builde a little pressure Ive had this problem on late models

bjtstarfire · 12-15-2006, 10:14 AM

Thanks guys

Oldsfan · 12-15-2006, 06:29 PM

Ben - yes, your best bet to check the HCV is to get the car up to operating temperature and then get a good vacuum source on the valve. You are right, the valve is always closed and applying vacuum opens it and allows coolant into the core. If you perform this test and get heat, then the problem is in the thermostat mounted on the heater case inside the car (and I'll be that is where the problem is because they tend to go bad with age). If you don't get heat with this test, then the HCV is bad. If you want to test the thermostat, hook a vacuum gage on the hose that connects onto the HCV. See if it's getting good vacuum or not.

Paul

12-14-2006, 04:59 PM	#1 (permalink)
bjtstarfire Member Join Date: Nov 2006 Location: Greater Philadelphia, PA area Posts: 65	Heater control valve What is the best way to check the operation of a HCV on a 61 Olds (It is vac. operated) or the heater t-stat? Should I just connect the vac line from the HCV that goes to the t-stat directly to a vac source? Is the valve normally closed then opened when vac is applied? Some background: Heater core is not blocked, water pump is good, coolent level is correct, hoses are fine, no air bubble. When the heater is on the fan blows cool air so the blower motor is functioning and the vac that controls the master blower switch mounted on the heater core blower housing, inside the engine bay, is good. Ben Happy Holidays and Motoring (When me and my daughter go for rides looking at the Christmas lights it gets pretty cold - she needs a blanket due to no heat). __________________ Ben '61 Starfire

12-15-2006, 05:10 AM	#2 (permalink)
Oldsguy Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 2,762	sounds like you are going to do it right, another way to gaurantee that water is flowing through the core is to simply leave the return hose to the control valve open and let it dump down the side of the engine in the front of the firewall. I would think that as soon as you start the engine the water will start flowing as the water pump is not clutch operated, you should only have to let it dump for a few seconds. Of course the water would still be cool but that would verify circulation to the valve inlet AT LEAST. Then you can also, try running it w/o the valve. After the engine heats up you should have HOT air through your vents unless there is some other problem. That's my two cents anyway. __________________ Dan '46 2 door

12-15-2006, 07:38 AM	#3 (permalink)
ozoneblue Senior Member Join Date: Jun 2006 Posts: 404	No heat Try installing a flush T in the return hose unscrew cap to bleed system.Also make shure you have a good radiator cap so the system builde a little pressure Ive had this problem on late models

12-15-2006, 10:14 AM	#4 (permalink)
bjtstarfire Member Join Date: Nov 2006 Location: Greater Philadelphia, PA area Posts: 65	Thanks guys __________________ Ben '61 Starfire

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12-15-2006, 06:29 PM	#5 (permalink)
Oldsfan Senior Member Join Date: Jul 2006 Posts: 474	Ben - yes, your best bet to check the HCV is to get the car up to operating temperature and then get a good vacuum source on the valve. You are right, the valve is always closed and applying vacuum opens it and allows coolant into the core. If you perform this test and get heat, then the problem is in the thermostat mounted on the heater case inside the car (and I'll be that is where the problem is because they tend to go bad with age). If you don't get heat with this test, then the HCV is bad. If you want to test the thermostat, hook a vacuum gage on the hose that connects onto the HCV. See if it's getting good vacuum or not. Paul