AC Clutch wont Engage

[Sasalmond]

Hopefully you guys can shed some light on my issue, i have been struggling with my 73 dart /6 ac. I have got my blower to finally function and the system appears to have refrigerant in it though i am not sure how much or the last time the ac was ever used on the car. I jumped the pressure switch to see if the clutch would lock and i got nothing, i than jumped the clutch to a 12v source just to make sure it still functioned and it locked right up. so after some reading in the FSM i noticed a second switch they call an anti freeze switch so i went ahead and jumped that switch and again the pressure switch and it finally locked in. So i assume that the system may be low due to the fact that i had to jump the pressure switch also but my question is would low refrigerant also cause the anti freeze switch to not engage or is that a whole different issue all together. Also i did test everything first with my multi-meter and i was only getting .03V at the pressure switch with no jumper wires being used.

 

[mderoy340]

anti freeze switch should have continuity when warm, opens circuit when cold. Low pressure switch is open when pressure is low, around 20 psi. You really need to put some gauges on it and see if the charge is low.

 

[Sasalmond]

Unfortunately i do not have a gauge set for r12 only 134a, is there a way i can test the switch to see if it has failed? Based on what you said about its operation it should be sending power to the pressure switch considering it is 90+ degrees ambient yet it is not sending power past it unless a jumper wire is used.

 

[67Dart273]

There's no reason you cannot use an R-134A gauge set, but you'll have to Google and download an R12 press-temp chart (Actually there's one in the shop manual I think.)

But the gauges will tell you nothing about that switch. I can't find a pictorial of it, but on the older cars, it is a cap tube sensor type thermostat that is buried in the coils of the evap

In a "general way" the switch would look something like this: