Heater not working

[David T]

While the valve is a likely cause of the non-flow, if you have a heater core that has not been flowing for a looong time, it is also possible the heater core is plugged up. The passages inside are small and over time old coolant gels and hardens. I would disconnect the heater hoses at the motor and loosely (so you don't build up too much pressure) use a garden hose and see if you can get any flow through the heater hoses and heater core. Once you know you have good flow you can work on the valve. Very common for the valves to leak and get stuck.

[DMC5180]

Yeah, the heater core connection tubes are quite soft. Several years ago when I did an evaporator replacement, I removed the heater hoses and found one tube was severely crushed from overnighting the hose clamp. That said, it never leaked and did not effect heating performance. I was fortunate in that I was able to reopen and reshape the tube to be fully round again.

[Cone]

I found that one of the metal coolant lines running up to the front of the car was totally plugged with crud! Still need to get that fixed. It’d be nice to have a functioning heater in Oregon.

[dn010]

I'd check to see if the control cable is attached at the temp switch and at the box before messing around with hoses and coolant.

[David T]

I'd check to see if the control cable is attached at the temp switch and at the box before messing around with hoses and coolant.

This will have no effect if the coolant isn't circulating in the heater core. Another thing to watch for, where the rubber hoses attach to the long aluminum coolant pipes, you get pinholes from corrosion. When it is really bad pieces will have dissolved from the ends of the pipes. You can either get longer hoses or new pipes. Way back, an owner bought a car and the engine was complexity clogged with gelled coolant. I forgot what he did to clean it out. This can happen because a car sits for a very long time and especially if different types of coolant ever got mixed. Some of the newer types of coolant do not mix well at all with other types. You can find all kinds of horror stories about this on the Internet.

[SBL]

Well, I pulled the hose at the heater core. Water was there, but it was not hot and did not flow. I hate getting in there with that valve. I have, in the past, caused added problems because it is hard for me to get to. Will have to pull it and check it.

[Rokkinlen]

What ended up being the problem?