85 Fleetwood Brougham Climate Control issue
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RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, 85 Fleetwood Brougham Climate Control issue in Past Cadillac Vehicle Discussion; I've discovered a nagging problem that I'd like to try and get on top of. The A/C doesn't always turn ...
  1. #1
    j2rossit is offline Cadillac Owners Enthusiast
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    85 Fleetwood Brougham Climate Control issue

    I've discovered a nagging problem that I'd like to try and get on top of.

    The A/C doesn't always turn on. Some times when I first jump in the car I'll need to turn the climate control on and off a few times before the compressor will kick on and start to blow cold air. Once the A/C starts, it seems to work fine after that, but the next time I jump in the car, again I'll have to play with the buttons for a while before it will kick on again.
    I don't know if it's related but I also have a problem where as I'm driving down the road occasionally the fan will turn off for about 2 seconds and then come back on to full strength. That happens once or twice a trip.

    I'm trying to figure out where to look first, climate control head? the control unit under the glove box? A bad ground somewhere?

    The lights on the climate control unit and the display always seem to look like they are doing what I expect, so it's not a contact problem with the buttons.

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    cadillac kevin's Avatar
    cadillac kevin is online now Cadillac Owners Master
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    Jon, if it's a problem with the CC head, I have a spare lying around (remanufactured delco)

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    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 85 Fleetwood Brougham Climate Control issue

    I haven't quite figured out how I'm going to test the components since it's just an intermittent problem. Another symptom I'm having is that if I leave the A/C on for a long highway trip, it seems to get weak and then quite after about an hour. After it sits for a few hours it comes back good as gold. But if I keep switching back and forth from auto to econ, it will work indefinitely. I'm wonder if the cycle switch at the evaporator is starting to give out.
    How much do you want for the CC head? I'm looking at getting one from a local wreckers if they'll ever send the guy out in the yard to see if the car's still there (they wont let outside people into their yard). Does anyone know if the units are standard and can be switched from metric to American units or if they are two separate part numbers?
    I have a brand new NOS resistor module in the car so I don't think it's related to that.

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    cadillac kevin's Avatar
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    Quote Originally Posted by j2rossit
    I haven't quite figured out how I'm going to test the components since it's just an intermittent problem. Another symptom I'm having is that if I leave the A/C on for a long highway trip, it seems to get weak and then quite after about an hour. After it sits for a few hours it comes back good as gold. But if I keep switching back and forth from auto to econ, it will work indefinitely. I'm wonder if the cycle switch at the evaporator is starting to give out.
    How much do you want for the CC head? I'm looking at getting one from a local wreckers if they'll ever send the guy out in the yard to see if the car's still there (they wont let outside people into their yard). Does anyone know if the units are standard and can be switched from metric to American units or if they are two separate part numbers?
    I have a brand new NOS resistor module in the car so I don't think it's related to that.
    30 bucks ok? BTW, I'll be getting a shipping quote on your 2nd box next week. All I have left is to get the alternator pulley off my dead 307 alt.

  6. #5
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 85 Fleetwood Brougham Climate Control issue

    Yeah, I'll take it for $30.

  7. #6
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 85 Fleetwood Brougham Climate Control issue

    Just to double check, the CC head you have is for the HT-4100 and has the rear window defroster?

  8. #7
    cadillac kevin's Avatar
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    Quote Originally Posted by j2rossit
    Just to double check, the CC head you have is for the HT-4100 and has the rear window defroster?
    I don't remember what year it is from. It is a direct fit for my 86, and has rear defroster. I don't know if the 307 units will work in the 4100 cars or not (if they look the same).

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    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 85 Fleetwood Brougham Climate Control issue

    The 4100 cars had the trouble code reader through the climate control head. It had a built in diagnostic for the TBI. Somehow I doubt the olds equipped cars had the same CC head.

  10. #9
    grauhst's Avatar
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    Re: 85 Fleetwood Brougham Climate Control issue

    They won't fit on HT4100 cars. You need a 82-85 one.
    Bought a later one too and saw that the Fuel Monitor is not working with this one.

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    cadillac kevin's Avatar
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    So would it have to be from a deville or would one from a 4100 powered eldorado work? It would have the diagnostics, but I am not 100% sure it is the same size/ has the same pinout.

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    grauhst's Avatar
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    Re: 85 Fleetwood Brougham Climate Control issue

    I think it doesn't matter, but no warranty to this.

  13. #12
    brougham is offline Cadillac Owners Master
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    Re: 85 Fleetwood Brougham Climate Control issue

    As long as the fuel data center isn't part of the control head itself it should be the same part.

    Remember that it won't blow cold all the time and the fan speed is also automatic. If the car senses that the interior temperature is where it should be the fan speed can lower and the ac won't come out as cold until it's needed again to maintain the temperature. If you have to turn it on and off a couple times to make it come on it could be that the blend door isn't working right.

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    Re: 85 Fleetwood Brougham Climate Control issue

    Quote Originally Posted by brougham View Post
    As long as the fuel data center isn't part of the control head itself it should be the same part.
    That doesn't matter. My FB with HT4100 has seperate control head and fuel monitor too.



    '86-'89 Brougham control head fit, but fuel data panel is not working with it. Just had this problem and unfortunately bought a '86-'89 one. Works great but as I said, no fuel monitor. The control head for HT4100 cars have another plug at the backside that goes to the fuel data display.
    Bought a correct '82-'85 one and now it works.

    Regards
    Felix

    ----------

    Here you can see the additional plug.
    In these two links are an Eldorado control head and a RWD control head. They have the same part number. So they all used the same control head on all HT4100 models.

    #1

    #2

    This one is a '86-'89 one. You can see the missing plug.

    #3

    Regards
    Felix

  15. #14
    mhamilton is offline Cadillac Owners Connoisseur
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    Re: 85 Fleetwood Brougham Climate Control issue

    Quote Originally Posted by j2rossit View Post
    I haven't quite figured out how I'm going to test the components since it's just an intermittent problem. Another symptom I'm having is that if I leave the A/C on for a long highway trip, it seems to get weak and then quite after about an hour. After it sits for a few hours it comes back good as gold. But if I keep switching back and forth from auto to econ, it will work indefinitely. I'm wonder if the cycle switch at the evaporator is starting to give out.
    How much do you want for the CC head? I'm looking at getting one from a local wreckers if they'll ever send the guy out in the yard to see if the car's still there (they wont let outside people into their yard). Does anyone know if the units are standard and can be switched from metric to American units or if they are two separate part numbers?
    I have a brand new NOS resistor module in the car so I don't think it's related to that.
    The evaporator is freezing up on highway trips... you're getting low on refrigerant. Don't just add indiscriminately, check the inlet and outlet temperatures of the evaporator lines while the ac is running, and check both high and low side pressures.

    For the issue where the ac is not engaging, check with a test light or voltmeter at the compressor clutch power connector when the ACC is on, but the compressor is not active. If you have 12V there, then nothing is wrong with your ACC. It would likely be a wide clutch gap or weak clutch coil. If not 12v, check for 12v at the evap pressure switch, then back to the ACC unit.

  16. #15
    j2rossit is offline Cadillac Owners Enthusiast
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    Re: 85 Fleetwood Brougham Climate Control issue

    Yeah, I think the evaporator is freezing which is why I'm suspicious of the cycle switch. It's supposed to shut the compressor off if the evaporator goes below 0 deg C and reengage the compressor when the evaporator warms to above 7 deg C.
    The system is charged and both high and low side pressures are good.
    I'll try and get what ever voltage readings I can when the system is giving me grief (it's been acting properly since I made the post here so I don't have much more to update). I hate intermittent problems.

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