News

A/C Problem Testarossa Cold then Heat

Discussion in 'Boxers/TR/M' started by Hawaii, Feb 4, 2010.

  1. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    Looking for help on my 91 testarossa.
    A/c works great and nice and cold but intermittantly all of a sudden heat starts coming out of the same vents. I shut it down and try it again them same thing... On it's own time or place.
    I'm Thinking the blend door is loosing vaccuum and letting hot air in or the water valve has a mind of it's own and letting hot water in??? I'm just guessing any help is appreciated!
    Thanks!
     
  2. kopiokosong

    kopiokosong Formula 3

    Sep 25, 2009
    2,374
    could this be related to the rather lousy fusebox that the trs have.
     
  3. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    Up date on the A/C. When I first start the car when cold at home.. hit the a/c recirc button and drive off...it seems to work perfectly and nice a cold (40degrees) After I shut down to get gas...and try to put it back on again it starts getting warmer and warmer. I put a thermometer in the vents and it got up to 110 degrees! If I drive around long enough with it boiling my peanuts off, it will cool off a bit but never get real cold again.
    something must be moving hot water into the evaporator box???
    I never use the heater here in Maui so i'm thinking of routing the hot water tube back into it self ...never letting it get to the evaporator box. Any body ever did that?
    Thanks for the help guys!

    PS It's had the Fuse Box upgrade..so I think that part is ok.
     
  4. Shamile

    Shamile F1 Veteran
    Silver Subscribed

    Dec 31, 2002
    6,563
    Lakeland FL
    Full Name:
    Shamile
    Dear Ferraristi,

    Are you sure the compressor is engaging?

    Is the condenser fan coming on?


    Hook up some AC gauges and see if your freon level is low.

    Tell us what you find.


    Shamile

    Freeze...Miami Vice !
     
  5. cryorunner

    cryorunner Karting

    Aug 11, 2009
    161
    San Diego, CA
    Full Name:
    James
    I'm sort of in the middle of fighting with my climate control problems, so I'm not quite up to speed yet and may not know what I'm talking about. But your later symptoms sound like my car, with total heat regardless of what the compressor is doing.

    In my case it's the "hot water cock" (gotta' love the service manual translations) which, near as I understand, allows hot water through the heater core when commanded or either unpowered (still need confirmation that it is normally-open) or just plain stuck open. Under correct operation it will be modulated by the climate control system to provide whatever heat is needed, and of course just close up when not needed during cooling. At the moment I have no +12V at the solenoid so regardless what the temp settings are it's HOT in any mode other than off.

    Also, my understanding is that you can't just bypass the hot water at the water solenoid, as it would just heat all the time. You'll need to bypass it coming from the engine (I believe this is under the car towards the cabin) or it may just be possible to clamp off the supply, maybe even up at the hot water cock, but I don't know if this would cause problems.
     
  6. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    Shamile
    I can hear the compressor clicking on when I hit the Recir button in my garage. Harder to hear when out and about when this problem occurs. I'm thinking since the heat is so hot 110 degrees that it must be hot water coming through the heater core. I will put gauges on it soon if nothing else works. It gets really cold when working so i'm thinking it must have a decent amount of freon charge too???
     
  7. ASG 86TR

    ASG 86TR Formula 3

    Aug 23, 2001
    1,473
    New Jersey
    Full Name:
    Adam G
    I have the opposite problem...I have great A/C, but no heat..or the heat will come on for a bit and then go cold....
     
  8. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    Haven't had time to check the hot water diverter yet but, when driving today the a/c was freezing cold so I turned the fan down a bit (thats all I touched) then heat started coming out of the vents for a couple blocks..just by moving the fan speed! Moved it back to high fan speed and a few blocks down the road it got cold again. Weird...
     
  9. Shamile

    Shamile F1 Veteran
    Silver Subscribed

    Dec 31, 2002
    6,563
    Lakeland FL
    Full Name:
    Shamile
    Dear Ferraristi,

    Did the fan speed change?

    Are the fan/ temp controls in the right place?

    I know...I know....sounds silly but never assume anything.


    Shamile

    Freeze....Miami Vice !
     
  10. GregTe

    GregTe Formula Junior

    May 3, 2004
    526
    Maine
    While we're on the climate control subject... Mine just stopped working along with the speedo. There is power at the fuses and relays but the system is totally dead, no fan running and the rear vent switches not lighting up. I can't understand why the speedo also went at the same time, do they grab power from the same place?
     
  11. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,148
    Texas
    Full Name:
    Steve Magnusson
    (Unless you've had a prior "fix" performed), the most likely place for your "no AC anything" trouble is at the connection in the "k" white connector IMO -- unplug the k connector and see if your connector position with the two M (brown) wires (one large, one small) looks anything like these (bad) examples (it's a common TR fault):
    Image Unavailable, Please Login
    Image Unavailable, Please Login
    Image Unavailable, Please Login
    Image Unavailable, Please Login

    There no obvious relationship (that I can see) between the AC system and the speedometer system -- maybe you are just lucky ;)
    Try a search on "116987" (which is the speedometer sender PN) for prior threads with (IIRC)some debugging info.
     
  12. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
     
  13. GregTe

    GregTe Formula Junior

    May 3, 2004
    526
    Maine
    Steve,

    Thank you the quick reply, I'll check it out tonight.

    Greg
     
  14. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    Just confirming that a/c cold air only comes out the center three vents?
    When does the round adjustible vents at the ends of the dash start working?
     
  15. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,148
    Texas
    Full Name:
    Steve Magnusson
    #15 Steve Magnusson, Feb 20, 2010
    Last edited: Feb 20, 2010
    The same "air" (cold or hot) that comes out of the center vents should also come out of the small round vents on the ends; however, they are connected by fairly longish, small, soft insulated tubes (that can get "smashed" closed) -- so don't expect a lot of air to come out there (see pages 45~46 in your OM).
     
  16. cryorunner

    cryorunner Karting

    Aug 11, 2009
    161
    San Diego, CA
    Full Name:
    James
    There's one weird connection that I only caught because it looked out of place while digging through Fig 9 (Fig 8 for the original manual) for my own problem. There's a G/yellow wire that runs through C5 "To 41 [Electronic Spedometer]." A quick look at Fig 7 (Fig 4 for the original manual) suggests it runs to some sort of back illumination at the speedo as well as other things, but I've never looked at that stuff before so I've got no clue how it's all is connected.

    Probably not related or much help, but it is a random connection between the A/C and the speedo.
     
  17. cryorunner

    cryorunner Karting

    Aug 11, 2009
    161
    San Diego, CA
    Full Name:
    James

    Remember, it's not really a "diverter" but rather just stops the flow of water from the engine into the heater core (when energized) or lets water flow (when unpowered). So you can't just bypass it in the passenger compartment (or you'd just get heat all the time), but you could conceivably clamp off a hose leading to/from it (looked too short/thick to me). It also means that if you're getting a blast of hot air you're probably thinking that you're losing power to the hot water solenoid.

    Of the two common big circuits that power the fan and the solenoid, Steve M. has already posted here about the K connectors (Hey! No fair using a pic of my super awesome car as an example of a "bad" Testarossa!). As I pointed out in your other thread about the interior lights, it is one possibility that a burned A/C pin here at this connector could also have taken out the neighboring pin for your lights, likely on the PCB.

    The other common circuit is on the ground side. Both the emitter for the blower transistor (and ground for the relay if at full speed I guess) and the switched ground side (through the relay) for the solenoid both get their ground at a single grounding point. While I haven't checked myself (not going back down there until I've got the passenger seat removed), I'm pretty sure this ground is made at a set of ground tabs located on the left side behind the plate at the front of the passenger footwell. Where ever it grounds, it will be a thick black wire off of pin 5 of the connector for the A/C unit. If this ground were poor and started floating around I could see having interactions between the fan and the solenoid.

    Just a thought. I'm still in the middle of my own troubleshooting here so still learning about this crazy system, but had been working on trying to annotate and highlight this part of the wiring diagram for myself. I'd still say making sure your voltage is good at the K connector during operation would be a first place to look. Anyone know which of these draws is responsible for most of this current and damage? Or what the current pull from the solenoid is in its "off" (energized) position is?
     
  18. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    James
    Thanks for the insight. That certainly makes sense to me. I'll try and check the grounds behind the plate and the connection at the fuse box and report back. Thanks!
     
  19. ryalex

    ryalex Two Time F1 World Champ
    Owner Consultant

    Aug 6, 2003
    22,026
    Las Vegas, NV
    Full Name:
    Ryan Alexander
    I take it that your car is a female.
     
  20. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    Thanks Steve.
    I don't anything from the drivers round vent. Not sure ont he passenger side. I'll have to check. I'll look for a collapsed hose under the dash.
     
  21. Shamile

    Shamile F1 Veteran
    Silver Subscribed

    Dec 31, 2002
    6,563
    Lakeland FL
    Full Name:
    Shamile
    #21 Shamile, Feb 21, 2010
    Last edited: Feb 21, 2010
    Dear Ferraristi,

     
  22. cryorunner

    cryorunner Karting

    Aug 11, 2009
    161
    San Diego, CA
    Full Name:
    James
    Probably need to correct myself here. While the relay to hold the solenoid valve closed shares the same ground, when not held closed it's under pulse-width modulation control from the A/C ECU, and that's on a different ground, but using the exact same 12V from the K connector 2nd pin. I'm still betting it's using that same grounding block with the multiple tab connectors, but have no real clue. Still, even more of a long-shot.

    Definitely checking the fuse box connector is a first step. I'm still hoping that this is part of your lighting riddle too.

    I'll trade you your solenoid with the clogged strainer for mine that's just always open. We don't need no stinking heat around here.
     
  23. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    Is there a trick to take out the white long plugs in the fuse box? I turned off the battery switch and a little scared to pull to hard on them puppies.
     
  24. cryorunner

    cryorunner Karting

    Aug 11, 2009
    161
    San Diego, CA
    Full Name:
    James
    On each end of the connector there's a clip that must be pressed in to release that side. Take your index fingers and place one against against each ridged end and then squeeze and pull. You'll feel the click. Because it's so tight in there I like to do the connectors on that side using a flat screwdriver to press the left side of the connector (facing the fuse box), but I can do it with my fingers as described. You can also kind of rock it by releasing the clip on just one side, but it tends to want to pop back in when you do the other side.

    OK, looking at that it doesn't look like it makes much sense. Sorry. Just disengage the clips on the sides, you'll figure it out.
     
  25. Hawaii

    Hawaii Formula Junior

    Jan 28, 2007
    847
    Maui
    Full Name:
    Emery
    LOL !
    Thanks for the quick response! I just don't want to wanker it up!
    I just took out my passenger seat to condition it later and to have more room to get to the kick panel and finally saw the Holy Grail of the water solenoid close up!
    I'll keep at it and report. Im also planning on switching the wearing drivers bolster with the passenger bolster! Good trick I learned here on the chat!
     

Share This Page