Page 2 of 2 FirstFirst 1 2
Results 11 to 16 of 16

Thread: A/C not blowing cold, but pressures are fine

  1. #11
    Senior Member DMC5180's Avatar
    Join Date:  May 2011

    Location:  Reedsburg, WI

    Posts:    3,738

    My VIN:    5180

    Club(s):   (DMWC) (DCUK)

    I would expect a plugged orifice to cause abnormally High side pressure. Unless the system is just very low on refrigerant.


    Sent from my iPhone using Tapatalk
    DENNIS

    VIN 5180, Frame 3652, STAGE I, DM-eng Solid State Solutions (RPM Rly, Dm.Lt.Mod., Fan Fail Mod. , FAN Rly, HS.Rly) , HID sealed beam style headlights, SPAX user since 2009, Eibach springs, Mid-State Club Adj. Rear LCA's, DPNW poly-sway bar kit, DMCEU LCA Stabilizer link kit, DMCMW Illuminated door sills, Aussie Illuminated SS Shifter plate, GENUINE MOMO EVO Steering wheel, DELOREANA Extended View Side Mirrors w/ Heaters, DELOREANA LED Door Lights.

  2. #12
    Delorean Guru
    Join Date:  May 2011

    Location:  Northern NJ

    Posts:    6,612

    My VIN:    10757

    Club(s):   (DMA)

    One way to check what is going on is to remove and measure the amount of refrigerant. For the pressures to look correct and no cooling several things would have to be bad at the same time. Verify you are moving enough air over both coils. It is possible to have the correct high side pressure with low refrigerant if the condenser coil is not dissipating heat because of insufficient airflow due to bad fans or dirt blocking airflow. On the low side the evap coil could be freezing over.
    David Teitelbaum

  3. #13
    Senior Member
    Join Date:  Dec 2016

    Posts:    198

    One scenario that would explain the AC working but no cooling is the heating is stuck on and working simultaneously. Combination of evaporator cooling plus heating coil heat gives you warm air. You should be able to eliminate the heat by putting the mode switch to MAX. But that assumes your heat valve works. Observe and verify that the heating valve is closing when MAX is selected. Even if it looks like it's working, you could clamp the heater hose near the valve to close it off for testing.

    Heater Valve sketch.JPG

    If you find the heating coil is the culprit, you'll need to look into the heat flap to see why the cooling from your evaporator is going thru the heating coil. Normally this is regulated by your temperature control knob.
    Ron

  4. #14
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    7,019

    My VIN:    03572

    Quote Originally Posted by DMC5180 View Post
    I would expect a plugged orifice to cause abnormally High side pressure. Unless the system is just very low on refrigerant.


    Sent from my iPhone using Tapatalk
    I would expect that also but since the compressor shuts off at 30 PSI on the low side that may not be the case.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  5. #15
    Member Project Vixen's Avatar
    Join Date:  May 2011

    Location:  Cranberry Township, PA

    Posts:    51

    My VIN:    05927

    At present, I'm still leaning more towards some type of physical blockage in the airbox. First, I would believe it would be highly unusual for the compressor pressures, cycling, etc. to be perfectly in spec if there were problems in that part of the system. Second, my wife said she thought there might be a mouse nest in the box as she saw little puffs of lint keep flying out of the round air portals on the sides of the dash for the door air vents.

    Some things I'm thinking I should try:
    • test the a/c with the car cold. Then there's no interference from the heater core
    • feel the accumulator/drier to see if it's getting cold.
    • drop the blower fan and look for signs of blockage
    • drop the bottom of the evaporator's housing
    • check the hot water valve, just because it was the last thing replaced.


    Thanks to all for the continued suggestions and help!

  6. #16
    Administrator Ron's Avatar
    Join Date:  Jun 2011

    Location:  North GA

    Posts:    4,532

    Club(s):   (SEDOC) (DCUK)

    Quote Originally Posted by Project Vixen View Post
    At present, I'm still leaning more towards some type of physical blockage in the airbox. First, I would believe it would be highly unusual for the compressor pressures, cycling, etc. to be perfectly in spec if there were problems in that part of the system. Second, my wife said she thought there might be a mouse nest in the box as she saw little puffs of lint keep flying out of the round air portals on the sides of the dash for the door air vents.

    Some things I'm thinking I should try:
    • test the a/c with the car cold. Then there's no interference from the heater core
    • feel the accumulator/drier to see if it's getting cold.
    • drop the blower fan and look for signs of blockage
    • drop the bottom of the evaporator's housing
    • check the hot water valve, just because it was the last thing replaced.!
    Sounds like a diverter/duct problem to me too (if accumulator cold).

    ====

    fwiw, a partially restricted orifice would make the high side go high and the low side go low. Blocked, the high side would go extremely high and the low side go negative (vacuum). Bypass LP Switch to test.
    If those pressure readings were taken when the clutch cycled out, they are near perfect for that ambient temp.

Page 2 of 2 FirstFirst 1 2

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •