Well I put away my 70 Stage 1 4spd 2day & took out my 70 Skylark convertible 350 with AC and after a 10 mile drive only cold air coming out of heater. One hose 2 heater core is hot & one is cold. There is no heater ctrl valve between the engine & firewall. After laying under dash for a while the blend door is moving when I move the temp switch. Also when I switch from heat to vents to defrost the air moves from the floor to dash to defrost. The car has been garaged for the last few months & I believe the heat was working last spring. Car has new hoses 4 core radiator & antifreeze. Is there a htr ctrl valve under the dash? of course my chassis manual is at a friends house who is away till next week. Any help is appreciated.
I'm leaning 2 a plugged heater core. Going 2 flush the system & c if I can blow some air through the heater core.
I assume if there's no heater control valve between the engine & firewall the car doesn't have one. Anyone know if they were built that way? will lay under dash after Turkey day.
No question, if it's a factory AC car...it should have a heater valve. It should be located about 6" from the front heater hose fitting on the intake manifold. There isn't one under the dash. That valve is connected to vacuum, so someplace somebody plugged, tee'ed or mickey moused your vac system of hoses under the dash. I really don't see how all the vent positions can work w/o it. Regardless....you should still have heat in both hoses, so it sounds like a plugged heater core.
I had the same situation last fall on my 64 Skylark. I don't have a/c, but the hoses should still be hot if the valve by manifold is open. My heater core was clogged. I flushed it out in reverse flow direction with garden hose. I also had blockage in the nipple on water pump where heater hose attaches. Once I got these two areas cleared, the heater blew nice and warm.
Ty 4 the advice. No heater Control valve in engine compartment. Going 2 flush the system out. Under the dash 2 the left side of the floor vents there is a big round disc with a vacuum line coming out at a 45 degree angle. maybe that's controlling the vent/dash/floor settings. Wish I had the chassis manual. I loveeeeeee when people borrow stuff tools/manuals etc & never return it. I go out and buy a new 4.5 inch grinder the other day cause I couldn't find mine. I know I have 1. I needed it 2 work on the pool truck. Anyway 2 days later my brother in law says BTW I still have your grinder in my garage..WTF!!!!Any way Happy Thanksgiving to all.
Happy Thanksgiving to you as well. Let us know how you flush the heater core out. I have a feeling I will need to do the same thing as I also have no heat in my convertible. I do have the heater control valve and both hoses are hot going to the firewall so now I'm thinking a blockage in the heater core (which was supposedly replaced before I purchased the Buick)
The heater valve is really only needed for the AC. By shutting off the hot water flow, you can get the AC colder.
When I flushed mine, I took the heater hoses off the heater core nipples and kinked those so it wouldn't lose much coolant from radiator or engine. Then I put some spare heater hose on the heater core. The one I had for the outlet I put into a five gallon bucket to catch all the mess from going all over the engine compartment and driveway. I used a nozzle on the garden hose that would insert into the other heater hose enough to keep from going all over. Before flushing job, the hose from the block would be real hot and the hose going from heater core to water pump would be fairly warm close to core. At the water pump the hose would be barely warm. I ended up doing this twice because the first time I didn't know the water pump nipple was clogged with jelled up anti freeze. So if flushing core doesn't take care of it, might try checking the water pump connection. Good luck, and Happy Thanksgiving!
Well I had a little time 2 kill 2day so I disconnected the heater hoses on the engine & blew through in the opposite direction & it seem 2 have fixed it. Now hose from engine is hot & hose returning 2 water pump is almost as hot. nice warm air coming in vents in car. woooohooooo. I'm going 2 hook up a garden hose to the heater core hose tomorrow & then install a flush kit & flush the whole system. Pretty easy fix. I guess the heater control valve was removed by the previous owner who was the original owner. It is a factory ac convertible. TY 4 all the advice.
