: Need help!!! did the bypass hcv mod and now i dont get heat

11-24-12, 10:01 PM
hi guys, here is what the problem is..had a coolant leak and it was the heater control valve so what i did is remove the hcv and did a bypass using T connector (followed the post here) and it fixed the leak but now i dont have any heat inside the cabin its blowing cold air, when it was leaking its still blowing hot air. and also my aux heat pump (located under the coolant reservoir) doesnt work is this pump supposed to pump coolant thru the heater core? the 2 heater hose connected to it does not heat up at all and when i followed the hose one goes to the heater goes and the other one to the hcv (bottom). could i just remove the aux pump and just directly hook it up to the heater core? any help or suggestions would be great. thanks

11-25-12, 07:14 AM
You're kidding us, right? You remove and bypass the assembly that controls the cabin temperature and then wonder why you have no heat? If you live in an area where you needed heat eventually why didn't you just replace the HBV instead of yanking it? That valve controls the flow of hot coolant through the heater core according to the setting of the temperature selector on the dash's HVAV. Solution? Buy a HBV and install it.

11-25-12, 11:08 AM
He,s right, without the HCV, when you turn on the heat, it inturns turns on the pump them inturns opens the bypass value, and there's senors everywhere to check temperture , by puting a T the coolant just flows to the T then back to the engene, not going to the inside. oh alittle will go but not enough to heat inside,

11-25-12, 12:02 PM
this is what i did. by catera00

11-25-12, 05:54 PM
Look at his location.................Tucson Arizona.

11-25-12, 08:23 PM
Just to expand on what gvjv3 said, the heater bypass valve (heater control valve) doesn't actually control the temperature of the heater. The bypass valve is like a switch that directs the flow to the heater, or when the A/C is on full, it directs the hot water back to the engine so that the cold air is not competing with a hot heater core. By putting in a T, you are splitting the flow, so only some of the hot water gets to the heater all the time, although I would guess that there is more back pressure in the water flow through the heater core, so most of the hot water would take the easier path to the engine, thus no heat. Water would just rather flow back to the engine through a nice thick hose than the passages of a heater core that may already be partially blocked in a car this old.

You either want to put a new HCV in (better), or get a nipple and connect the heater up permanently, forgetting about the bypass feature. Your A/C may not get as cold that way.

11-26-12, 09:14 AM
that was my purpose is to completely bypass the HCV...also just found out that my aux heat pump is not working so this will make it more hard for the coolant to flow thru the heater core. im also thinking maybe doing a manual switch for the flow of the coolant to the heater core (have to check in home depot) so this way i can turn off the coolant going thru the heater core in summmer and turn it back on again in winter.

11-27-12, 05:16 PM
its fixed now i get heat. it was my aux heat pump thats not working pick one up at the junk yard and its all wrking now.