75 dart sport AC heater control valve pic

[chargers777]

Nothing on the heater hoses. We just got the car and no heat. Is it vacuum activated? This car originally had AC.

 

[CRUZE 418]

I would say yes if it had A/C. These are of my '72, but would bet they are almost the same.

 

[chargers777]

Thanks for the pics but mine isn't on the heater hoses.

 

[RustyRatRod]

Thanks for the pics but mine isn't on the heater hoses.

What he's trying to tell you is, that's where it's supposed to be. Evidently, it's been removed.

 

[Jim Kueneman]

Probably removed. The problem is no one makes them and they are 2 different hose sizes on each end. Is there some sort of adapter in that line to change diameters?

Jim

 

[Vaanth]

Nothing on the heater hoses. We just got the car and no heat. Is it vacuum activated? This car originally had AC.

The 1975 Dart Sport with air conditioning was originally equipped with water valve, or heater control valve, part number 3879337. The valve is actuated by vacuum routed from the dash mounted control switch.

The image in post #2 shows the area in which the valve is located, but the later valve configuration differs. The following images show an original Chrysler replacement 3879337 valve, which differs in appearance from production units:

The following image shows a production style heater control valve for this applications and some others:

The following images show diagrams of the valve mounting and hose layout for 1975 A-body six cylinder and eight cylinder applications.

Valve number 3879337 was used in 1975 and 1976 (built until 6-1-1976) A-bodies with air conditioning, and in 1975 and 1976 B-bodies without air conditioning.

Valve number 3879337 has a 1/2″ hose nipple and a 5/8″ hose nipple with a metal mounting bracket, and a vacuum diaphragm pod with the vacuum nipple on the top. Note that the bracket is marked with number 3502487.

The following list shows some aftermarket replacement valves. These are discontinued but can still be found.

• Everco H2993
• Four Seasons 74667
• AC Delco 15-5163
• Dole DW-48
• Stant H-155

Note that aftermarket configurations differ and some do not have a mounting bracket. Other applications or styles can be adapted. The following images shows different Chrysler and aftermarket valves, including the later plastic housing style that could be used:

Depending on the valve used, differing hose sizes can be joined with hose couple like those shown in the following image:

 

[townsend]

It would be helpful to have photos of chargers777 engine compartment.

 

[Mike69cuda]

If there is no valve you should have heat all the time. Vavle shuts off the flow from engine.

 

[chargers777]

The 1975 Dart Sport with air conditioning was originally equipped with water valve, or heater control valve, part number 3879337. The valve is actuated by vacuum routed from the dash mounted control switch.

The image in post #2 shows the area in which the valve is located, but the later valve configuration differs. The following images show an original Chrysler replacement 3879337 valve, which differs in appearance from production units:
View attachment 1716488040
View attachment 1716488041

The following image shows a production style heater control valve for this applications and some others:
View attachment 1716488150

The following images show diagrams of the valve mounting and hose layout for 1975 A-body six cylinder and eight cylinder applications.
View attachment 1716488039
View attachment 1716488038

Valve number 3879337 was used in 1975 and 1976 (built until 6-1-1976) A-bodies with air conditioning, and in 1975 and 1976 B-bodies without air conditioning.

Valve number 3879337 has a 1/2″ hose nipple and a 5/8″ hose nipple with a metal mounting bracket, and a vacuum diaphragm pod with the vacuum nipple on the top. Note that the bracket is marked with number 3502487.

The following list shows some aftermarket replacement valves. These are discontinued but can still be found.

• Everco H2993
• Four Seasons 74667
• AC Delco 15-5163
• Dole DW-48
• Stant H-155

Note that aftermarket configurations differ and some do not have a mounting bracket. Other applications or styles can be adapted. The following images shows different Chrysler and aftermarket valves, including the later plastic housing style that could be used:
View attachment 1716488149

Depending on the valve used, differing hose sizes can be joined with hose couple like those shown in the following image:
View attachment 1716488151

Thank you for the very detailed information. I appreciate your response. I can now look for the correct valve. I wanted to make sure it wasn't mounted on the heater box.

 

[chargers777]

If there is no valve you should have heat all the time. Vavle shuts off the flow from engine.

I have no heat at all.

 

[Mike69cuda]

With the engine on, when you move the lever from defrost, heat, ac, does the air flow change to different vents? Im wondering if your vacuum is hooked up and moving the actuators.

 

[chargers777]

No it doesn't change

 

[townsend]

The vacuum hose diagrams for the 73-76 Abodies are identical.
Go to the 1973 Dodge chassis service manual at mymopar.
Starting at the bottom of page 24 - 42, you will find the description of the heat - ac system, including vacuum diagrams.

 

[Mike69cuda]

Sounds like there is no vacuum system operation. I am not very familiar with the 73 & up heat & ac, but there should be two vacuum hoses coming through the firewall. One should go to engine manifold vacuum to supply vacuum to the vacuum switch in the dash. That is a possible cause.

The dash vacuum switches often fail, particularly after 50 years.