What Next? 1973 Ford Contry Sedan

Discussion in 'General Automotive Tech' started by Slidemanic, Oct 11, 2016.

  1. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

    Joined:
    Apr 21, 2014
    Messages:
    14,928
    Likes Received:
    2,950
    Trophy Points:
    710
    Location:
    New Braunfels, TX
    I'll do some checking in my books, but if I'm reading your post correctly, not only is it not blowing cold, but the blower stops turning? The only commonality to both those circuits would be the HVAC control panel. Once you move from OFF, at the very least, you should have HI in all settings. Does the blower cut out on HEAT? Then, whether the blower is running or not, when you set it to MAX or AC, does the clutch short-cycle (turns on for a couple seconds, but can stay off from a few seconds to a few minutes)? Or does it just not cycle at all?
     
  2. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

    Joined:
    Apr 21, 2014
    Messages:
    14,928
    Likes Received:
    2,950
    Trophy Points:
    710
    Location:
    New Braunfels, TX
    One other thing: check the fuse block, see if someone put a 30 amp CB in, in place of a fuse. If the system draws too much amperage with a CB, it'll cycle on and off.
     
  3. Grizz

    Grizz Are we there yet???

    Joined:
    Mar 4, 2016
    Messages:
    2,410
    Likes Received:
    982
    Trophy Points:
    398
    Wagon Garage:
    1
    Location:
    Nashville, TN
    I might be way off here but doesn't a lack of refrigerant prevent the compressor from engaging? I could be making that up like I do slot of stuff. Could be it was working fine but has a slow leak?
     
  4. OldFox

    OldFox Curmudgeon

    Joined:
    Feb 20, 2013
    Messages:
    1,318
    Likes Received:
    338
    Trophy Points:
    195
    Location:
    West Tn
    It should have a sight glass to check the freon.
     
  5. Slidemanic

    Slidemanic Well-Known Member

    Joined:
    Dec 10, 2014
    Messages:
    368
    Likes Received:
    23
    Trophy Points:
    45
    Location:
    Northeastern USA
    No Freon anymore,it's charged with R134a. I haven't seen a sight glass,my '77 Country Squire had one years ago,so you'd think there'd be one. One other thing is that the fuse panel doesn't match with the one in the Owner's Manual,which shows a 4 Amp. fuse for AC/ATC or a 15 Amp. fuse for Heater only. (No ATC on this car). It seems that the charge is OK,because when the system comes back on,it is just as cold as before it cut out. It's cooler out today,and I have to go to work,so I can't look at it right now,and may just open a window.
     
  6. Grizz

    Grizz Are we there yet???

    Joined:
    Mar 4, 2016
    Messages:
    2,410
    Likes Received:
    982
    Trophy Points:
    398
    Wagon Garage:
    1
    Location:
    Nashville, TN
    Sounds like a leak, but the shop that charged it should have tested this. Also do you know it they put any dye in the system? A lot of the times the valves or rubber o rings go bad on the high/low service ports. You might be able to visibly see a leak around these ports
     
  7. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

    Joined:
    Apr 21, 2014
    Messages:
    14,928
    Likes Received:
    2,950
    Trophy Points:
    710
    Location:
    New Braunfels, TX
    I would say there's no leak, but that the system loses power to run when it stops. If it were a low charge problem, the blower would still run when the compressor stopped.
     
  8. Grizz

    Grizz Are we there yet???

    Joined:
    Mar 4, 2016
    Messages:
    2,410
    Likes Received:
    982
    Trophy Points:
    398
    Wagon Garage:
    1
    Location:
    Nashville, TN
    Oooo, I missed the part about the blower motor cutting out:slap:
     
  9. Thirsty islander

    Thirsty islander Well-Known Member

    Joined:
    Apr 23, 2012
    Messages:
    490
    Likes Received:
    116
    Trophy Points:
    102
    Location:
    Windsor, Ontario, Canada
    I'll go out on a limb and call it a vacuum leak. Ok it most likely is a vacuum leak. No wait it definitely is a vacuum leak.
    I have not worked on my 77 colony parks system as it's working fine, but I have disassembled my 64 Cadillacs climate control and they appear to be very similar. There are multiple independent systems working together to form the climate control in these cars. The a/c, heater, electrical, vacuum and thermistors. The first thing I would check is that the evaporator is not freezing up. That would make it appear that the fan is not running. If you park the car after it stops working and you end up with a big water puddle underneath it, then that could be the cause of it cutting out, as the evaporator has frozen solid. Once you have ruled that out then you have to start looking for vacuum leaks. While looking for leaks you also have to look to see if you have any one way valves in the system. If these valves deteriorate then you will have your system cycling as there needs to be a constant vacuum source. On the caddy there is a vacuum servo that positions the the systems operating a parameters based on what the thermistors are telling it to do. So a low vacuum signal will be full a/c and a high vacuum signal will be full heat. Both of those positions give full fan speed and all vacuums positions in between will be variances of heat and a/c and fan speeds based on temps in and out of the car. Although it will appear that everything is tied together by electricity it's actually vacuum that's the common thread. So when we loose vacuum we get all kinds of wonky things going on and the system can't compensate. Power servos are, as I've stated earlier, are vacuum controlled. So since I can't speak specifically to the Ford systems I will give some general numbers to help you understand what's going on. Let's say the power servos operating vacuums are 3" to 18", so three inches of vacuum give full a/c and 18 inches gives full heat. (It could be reversed of this, but we are talking in general terms) The servo arm moves and makes contact on different circuit board positions and sends vacuum to different mode doors based on its amount of vacuum. It gets that vacuum signal from a transducer that interprets electrical signals and turns them into vacuum signals. The transducer at times will get dirty and not allow proper vacuum to the power servo. The transducers vacuum valve is just like a sink tap. It's open a little and you get a little vacuum. It's opened a lot and you get a lot of vacuum. If it wears out and deteriorates then you get very little vacuum and if it gets dirty then you can end up with too much vacuum. Thus messing up your system making you spend lots of that hard earned cash paying people who tell you they know a/c systems but in reality have no clue on how to fix climate control systems. Good luck
     
  10. Thirsty islander

    Thirsty islander Well-Known Member

    Joined:
    Apr 23, 2012
    Messages:
    490
    Likes Received:
    116
    Trophy Points:
    102
    Location:
    Windsor, Ontario, Canada
    Is your a/c system a factory installed part or dealer installed part?
     
  11. Slidemanic

    Slidemanic Well-Known Member

    Joined:
    Dec 10, 2014
    Messages:
    368
    Likes Received:
    23
    Trophy Points:
    45
    Location:
    Northeastern USA
    Hoo boy what a frazzle. I missed the part in the manual where it says 30 Amp CB for AC/ATC! That slot is listed as a 15 Amp heater fuse,but footnote says 30 Amp CB w/AC/ATC. So best guess as to what is happening is that the tired old CB cuts out under stress,and for awhile won't let any climate control happen. My parts guys at Ford dug deep and found a replacement CB. These are designed to fit where a glass fuse fits:no blades. $15.00. So another antique "once they made 'em this way" part. It got a tad warm today and the AC didn't cut out. Stereo won't come on though.
    It is a factory AC with the big squarish compressor that at some point since 2010 was reborn as R134a.
    In 1973,they were putting systems on top if systems,mainly concerned with keeping ahead of Federal emissions & safety regulations,so...two flashers,two different circuit breakers,not to mention all the fusible links...
     
    ModelT1 likes this.
  12. Thirsty islander

    Thirsty islander Well-Known Member

    Joined:
    Apr 23, 2012
    Messages:
    490
    Likes Received:
    116
    Trophy Points:
    102
    Location:
    Windsor, Ontario, Canada
    I think in 77 the square ones were dealer installed. Factory were the a6 compressors.
     
  13. OldFox

    OldFox Curmudgeon

    Joined:
    Feb 20, 2013
    Messages:
    1,318
    Likes Received:
    338
    Trophy Points:
    195
    Location:
    West Tn
    Regardless of the problem, one of the first things I would check is the drain valve in the bottom of the evap case. They often plug up and allow water to collect inside the case.
     
  14. Leadslead

    Leadslead Well-Known Member

    Joined:
    May 20, 2016
    Messages:
    799
    Likes Received:
    328
    Trophy Points:
    166
    If its a vacuum problem the blower motor would still function it would just blow out of the defrost (top of dash) vent, Ford did a safety thing with their vacuum system on a lot of things... your heat and a/c could crap out but you'd still have defrost, if you had hidden headlamps and the vacuum crapped out the doors would open, things like that, this is directly from the 1973 ford service manuals.
     
  15. Slidemanic

    Slidemanic Well-Known Member

    Joined:
    Dec 10, 2014
    Messages:
    368
    Likes Received:
    23
    Trophy Points:
    45
    Location:
    Northeastern USA
    The vacuum system was thoroughly checked when I had the ignition/driveability issues. The other thing happening now is that on first cold startup,nothing happens for awhile when you put the lever in D. Drive a bit,and it engages normally. My idea is to do C6 band adjustment per the manual. The other thing is that the rear Trac-Lok axle is getting noisy--and it has been diagnosed as weak already. No lack of 90W gear oil,although there is seepage at the front seal. Shift R to D & v.v. & you get a clunk most times. The axle genius says $8/900.00,but then it's like new. All that and finding 2-3 wheels 6.5x15 to replace the bent ones would make my day.
     

Share This Page