Hot in cab when driving

[Ash84]

Hey fellas I got a 50 Plymouth handed to me so I'm trying to figure out all the kinks. When I'm driving it feels like the heater is on even when I have it all turned off. Can any one give a clues, is there a thermostat valve I'm missing?

[keithb7]

Blower motor stuck on, or wired on full time? Is a blower motor actually blowing hot air into the cab?

[allbizz49]

There  might be a valve to turn the hot water off so it doesn't flow through the heater. My 49 and 53 both have them. My 53 has "summer" with an arrow pointing in the direction to shut the water off on the heater box. 

Edited September 4, 2021 by allbizz49

[Doug&Deb]

Is there a valve screwed into the rear of the cylinder head? Some applications have a shutoff valve for the heater.

[busycoupe]

There should be a thick sisal pad on the inside of the firewall to insulate for heat and sound.  Even with that pad in place and the heat shut off, my coupe gets quite warm.  It is pleasant in cool weather, not so much in warm weather.  I think these cars just get hot in the cab from engine and exhaust heat.

[Sniper]

My 51 has a water shut off valve AND an air shut off flap in the duct work.

 

Neither really help so I think busycoupe is on to something.

[greg g]

Cowl vent opening all the way? Shutoff closing all the way?  You can take off the feed hose and make a wood plug and clamp it or hook the feed line to the return line with a piece of copper tube clamped in place and bypass the heater.  My car has a sheet metal heat shield between the passenger side foot well and the exhaust pipe, is yours present and in place?

[Ash84]

21 hours ago, keithb7 said:

Blower motor stuck on, or wired on full time? Is a blower motor actually blowing hot air into the cab?

It seems the same with it on or off to day I turned it on to get some air flow with windows, because my hood vent will only open a 1/4 way open. 

[Ash84]

20 hours ago, allbizz49 said:

There  might be a valve to turn the hot water off so it doesn't flow through the heater. My 49 and 53 both have them. My 53 has "summer" with an arrow pointing in the direction to shut the water off on the heater box. 

I thought there is a valve but I feel like a idiot don't know where it's located.

[Ash84]

13 hours ago, Doug&Deb said:

Is there a valve screwed into the rear of the cylinder head? Some applications have a shutoff valve for the heater.

I'v been told there is I will look in that location again.

[Ash84]

13 hours ago, busycoupe said:

There should be a thick sisal pad on the inside of the firewall to insulate for heat and sound.  Even with that pad in place and the heat shut off, my coupe gets quite warm.  It is pleasant in cool weather, not so much in warm weather.  I think these cars just get hot in the cab from engine and exhaust heat.

I figured they do to. I did have a decent ride to day because like you said it wasn't that hot out.

[Ash84]

12 hours ago, greg g said:

Cowl vent opening all the way? Shutoff closing all the way?  You can take off the feed hose and make a wood plug and clamp it or hook the feed line to the return line with a piece of copper tube clamped in place and bypass the heater.  My car has a sheet metal heat shield between the passenger side foot well and the exhaust pipe, is yours present and in place?

I will look for the heat shield , that's for the rigging idea will keep that in mind.

[Ash84]

Well I wish I would of looked at this post to day sence I was out driving you all been a big help. Thanks, I will post back with any results.

[Booger]

Maybe cut a piece of thermal blanket (the shiny stuff) to use under mat/carpet

[DJK]

Remove the duct work between the heater box and firewall, with engine up to temp., turn on blower motor, see if there is hot air coming from heater box. Once I adjusted the control arm on the heater box, hot air into the vehicle was eliminated on SUMMER setting.

[Sniper]

Some heater setups don't have a summer setting, mine doesn't.  Might have to remove the duct and cover the opening to the passenger compartment for summer use.

[Ash84]

3 minutes ago, Sniper said:

Some heater setups don't have a summer setting, mine doesn't.  Might have to remove the duct and cover the opening to the passenger compartment for summer use.

Mine looks like it was replaced with a hose returning to what I think is the blower bow ( that's my technical term)

[Ash84]

[Sniper]

That first picture you posted should be of a cable operated shut off valve.  You don;t have that which is why it's blowing hot air all the time.

 

I have one, still blows hot air but it might be leaking by internally.  You can buy a manual shut off valve, sort of like the valve you hook your garden hose to.  Close it in summer, open it for winter.

Edited September 9, 2021 by Sniper
not sure why something got censored, typo?

[DJK]

On 9/7/2021 at 8:04 PM, Sniper said:

Some heater setups don't have a summer setting, mine doesn't.  Might have to remove the duct and cover the opening to the passenger compartment for summer use.

Been there done that last summer, before I corrected the adjustment.

[Ash84]

On 9/7/2021 at 8:20 PM, Sniper said:

That first picture you posted should be of a cable operated shut off valve.  You don;t have that which is why it's blowing hot air all the time.

 

I have one, still blows hot air but it might be leaking by internally.  You can buy a manual shut off valve, sort of like the valve you hook your garden hose to.  Close it in summer, open it for winter.

OK good to know I'm getting car out tomorrow and getting my front cross member replaced at a classic car garage so I will ask him where i can get that set up. Im sure he will know what your talking about.

[Andydodge]

Ash.....just read this thread, hope you get the heat sorted out BUT........you mention getting the front crossmember replaced(!)...............whats the reason for that?........andyd