ConcoursMustang Forums

1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1971 - 1973 => Topic started by: 67foxgt390 on May 22, 2020, 07:44:36 PM

Title: 73 Cobra Jet Convertible AC questions
Post by: 67foxgt390 on May 22, 2020, 07:44:36 PM
 Hello Every one. Happy to be talking with such a great group. I'm working on my recently acquired 73 CJ conv. While testing some things I noticed that my AC does not blow cold but does seem to "work" I noticed that the heater hoses are not on the car " bypassed I guess" My question is will this prevent my AC from functioning properly? Looks like it might be a pain to replace! Any opinions on this would be appreciated. One more thing, Where are the oil pressure sending unit and the temp sending unit located? I never owned a 351 car! Of course i could find them on my old 390!! Thanks in advance!!  Chuck
Title: Re: 73 Cobra Jet Convertible AC questions
Post by: 67gta289 on May 22, 2020, 09:45:42 PM
The only ways for the heater to affect vent discharge temp when AC is operating that I can think of are:
(1) AC not set to max cool, and some of the heat from the heater coil is blended in, which would be normal
(2) AC set to max cool, but something with the heater shut off valve or valve control circuit has malfunctioned

But since it sounds like the heater core is bypassed, none of that would be relevant.  An A/C system is fairly complicated and much of it requires special tools and training.  If it gets cold, but not cold enough, you might get lucky and are just low on refrigerant. 

Regarding the sending units, I had to look this up, so no guarantees.

Temp - located below the thermostat. See pic.
Oil Press - located behind the intake manifold.
Title: Re: 73 Cobra Jet Convertible AC questions
Post by: J_Speegle on May 22, 2020, 10:50:09 PM
Temp - located below the thermostat. See pic.

Think you will find that the water temp is (in the picture) above and to the left attached to the front of the block. What you have circled is what is left of the PVS / Ported Vacuum Switch if I recall correctly. Too much stuff in the way on a fully assembled and installed engine
Title: Re: 73 Cobra Jet Convertible AC questions
Post by: rickmustang on May 24, 2020, 12:10:02 PM
Check if you have Freon pressure in the AC system first. If not, you have a decision to make about R134 as the original was R12 stuff but is hard to find and probably illegal. Compressor, clutch and expansion valve could all be issues.
Title: Re: 73 Cobra Jet Convertible AC questions
Post by: cobrajet_carl on May 24, 2020, 04:10:34 PM
Hello Every one. Happy to be talking with such a great group. I'm working on my recently acquired 73 CJ conv. While testing some things I noticed that my AC does not blow cold but does seem to "work" I noticed that the heater hoses are not on the car " bypassed I guess" My question is will this prevent my AC from functioning properly? Looks like it might be a pain to replace! Any opinions on this would be appreciated. One more thing, Where are the oil pressure sending unit and the temp sending unit located? I never owned a 351 car! Of course i could find them on my old 390!! Thanks in advance!!  Chuck
I had a 73 convertible that blew cool but not cold. Gauge readings were OK but compressor cycled on and off a lot. Turns out the de-icing sensor in the evaporator was turning the compressor off at about 50 degrees instead of the 35 or so that it should have been.
Title: Re: 73 Cobra Jet Convertible AC questions
Post by: cobrajet_carl on July 21, 2020, 01:42:59 PM
I meant to add that if you pull the glove box down the connector to the de-icing sensor is right there. You can jumper it pretty easily.