'64 Heater only blows Cold

[Ron S.]

Can one access the heater doors thru the glove compartment? These open & close I understand, am thinking if stuck in the closed position, I will never get heat. Car has a new DeWitt's correct alum radiator, and all hoses routed correctly. Fan blows but no heat. Temp gauge stays around 180 always. Far as I know, the heater core has never been out of the car---no evidence of any leaks in cockpit or firewall. Chime in for a first-time poster please. Thanks.
Ron

[Harry S.]

Re: '64 Heater only blows Cold

You can only access the cables that control the doors. It is possible a cable fell off. So remove the glovebok and take a look. Remember, the wire to the glove box light is always hot unless you disconnect the battery.

If the doors are moving, pull the fan and see if the squirrl cage came off the shaft. I've never seen that happen but?????

[David L.]

Re: '64 Heater only blows Cold

Ron,

Your heater core is probably partially or fully clogged. If it is original then it is 49 years old. I just unclogged the heater core in my 1998 Chevrolet S10 since I was getting very little heat. I disconnected the heater hoses at the block and then carefully flushed and back flushed the heater core several times with my garden hose as well as my air compressor (not to exceed 15 psi). I then replaced the 16 year old heater hoses and installed new antifreeze. It does not take much crud to clog the heater core. I now have plenty of heat in my S10.

I have also heard of just reversing the heater hoses (two 5/8" to 3/4" adapters are required) but the crud remains in the system.

A temperature "gun" can tell you the temperature at the heater core hose connections at the firewall. There was a substantial difference in temperature at the heater core connections on my S10 before I flushed the core.

Dave

[Domenic T.]

Re: '64 Heater only blows Cold

Ron,
All good advice but one more thing. Check the valve at the firewall and see if it is working. The cable opperates a vacume switch that opperates the valve.
I would do all the above if the valve is working.

DOM

[Donald O.]

Re: '64 Heater only blows Cold

Ron,
All good advice but one more thing. Check the valve at the firewall and see if it is working. The cable opperates a vacume switch that opperates the valve.
I would do all the above if the valve is working.

DOM

IIRC, that valve was only installed with air conditioning.

[Domenic T.]

Re: '64 Heater only blows Cold

Donald,
Thanks, I didn't think of that, I thought it was a A/C car.

DOM

[Rob M.]

Re: '64 Heater only blows Cold

Donald,
Thanks, I didn't think of that, I thought it was a A/C car.

DOM

make sure there is enough fluid in the whole system, when it gets below a certain level the interior heater circulation stops (at least that is what i found out on my '59

[John H.]

Re: '64 Heater only blows Cold

Can one access the heater doors thru the glove compartment? These open & close I understand, am thinking if stuck in the closed position, I will never get heat. Car has a new DeWitt's correct alum radiator, and all hoses routed correctly. Fan blows but no heat. Temp gauge stays around 180 always. Far as I know, the heater core has never been out of the car---no evidence of any leaks in cockpit or firewall. Chime in for a first-time poster please. Thanks.
Ron

Ron -

With the engine warmed up and running, is the lower 5/8" heater core inlet hose the same temperature as the upper 3/4" heater core outlet hose? If the core isn't clogged, the 3/4" outlet hose should be about the same temperature as the inlet hose, as the coolant flows all the time through the core at full rate regardless of the position of any of the doors inside the case (they only control airflow, not coolant flow).

[Ron S.]

Re: '64 Heater only blows Cold

Ron -

With the engine warmed up and running, is the lower 5/8" heater core inlet hose the same temperature as the upper 3/4" heater core outlet hose? If the core isn't clogged, the 3/4" outlet hose should be about the same temperature as the inlet hose, as the coolant flows all the time through the core at full rate regardless of the position of any of the doors inside the case (they only control airflow, not coolant flow).

Thanks all,....must be a clog, ran today about 22 minutes, and top hose cold bottom hose hot. Weird though top hose only from the T under the expansion tank is cold back to the firewall. Part of the top hose forward to the water pump was warm?? Clog in the T perhaps. Anyone heard of that?

[Donald O.]

Re: '64 Heater only blows Cold

If you have an original heater core, it might be what is clogged.
Put a needle nose vise grip pliers on ear hose and then blow air into either brass pipe of the hc and coolant should come spewing out the other pipe. If not, there's the clog. If if it does blow all the coolant out, then the clog is either at the TEE or the engine out port to the TEE.

DonO

[Jim T.]

Re: '64 Heater only blows Cold

In 1967 I bought a 63 Impala SS in San Diego, CA. Being a local car I could only imagine what was used for coolant when I found no heat coming from heater. Removed the heater hoses and flushed the heater core removing the "crud" and serviced the coolant system. Would not of expected this on a 4 year old car. It does get cold enough in San Diego to use a heater, witnessed it snowing one December day in 1967.

[John H.]

Re: '64 Heater only blows Cold

Thanks all,....must be a clog, ran today about 22 minutes, and top hose cold bottom hose hot. Weird though top hose only from the T under the expansion tank is cold back to the firewall. Part of the top hose forward to the water pump was warm?? Clog in the T perhaps. Anyone heard of that?

Ron -

The heater core is clogged - the 3/4" hose forward of the tee is warm due to convection from the water pump coolant, and it's cold from the tee to the firewall because the heater core inlet is clogged.

[Doug L.]

Re: '64 Heater only blows Cold

Given the frequency of leaks where the hoses connect at the firewall, with consequent water soaking the passenger side carpet, some have welded one side of the "T" outlet and the pipe at the intake manifold to block all water from the heater. Doug

[John H.]

Re: '64 Heater only blows Cold

Given the frequency of leaks where the hoses connect at the firewall, with consequent water soaking the passenger side carpet, some have welded one side of the "T" outlet and the pipe at the intake manifold to block all water from the heater. Doug

Doug -

That's exactly what you'll find on '67 L-88's and midyears with RPO C48 (heater delete), but it was done with two rubber caps - one on the 5/8" intake manifold fitting, and a 3/4" cap on the rear leg of the tee at the expansion tank.