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Way to bench test Automatic Heat control?
I am attempting the get the heat working on my car. It hasn’t worked since I owned it. One of the issues that I sure can use some technical direction with is the automatic heat control. When it was in the car, with the turnbuckle disconnected from the cables and power to it, the arm would not move much back and forth. It would nudge a tiny bit, that’s it. I am wondering if something internal to the heat control is frozen or needs some lubrication. What I’d like to know is if there is a way to test this function of the automatic heat control while it is out of the car, such as on workbench, by putting 12v to specific terminal to see if the arm moves back and forth. If this is possible, can anyone tell me how to do this?
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1986 930, Instant G 3.6 Varioram Conversion, Cyntex chip, cams, solid lifters, custom exhaust, G50 trans, 22mm front and 29 mm rear, tarrett sway bars front and rear, strut tower brace, brembos, 18" turbo twist wheels |
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01-07-2017, 06:55 AM
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Join Date: Apr 2005
Location: outta here
Posts: 53,202
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Before you do that, test both sensors on the car.
JR |
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01-07-2017, 07:06 AM
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^^^^+1
There is a procedure in Bentley for how to test the sensors by checking their resistance. My caloric sensor in the flapper was cashed, and a new one is like $450. Instead, there is a thread on here about using a $2.00 thermister from digi-key. I went that route and it works great. That being said, even though my caloric sensor was cashed, the flappers still opened and closed (i.e. the arm in the control box still moved. Perhaps your servo motor is perished. I don't know how to bench test this, however.
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1987 911 Carrera coupe - Guards Red 2010 997.2 C4S 6-Speed 2005 Mini Cooper Convertible (R52) - Wife's car 1977 VW Bay Window Camper Bus |
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01-07-2017, 07:16 AM
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Thanks all. I don't have a Bentley yet (on my short list of things to buy). I saw a procedure on how to test the rear sensor by the flapper (as noted above with a resistance check). However, I am unclear on how to test the front sensor.... where to find the wires for the front sensor (mine is on my dashboard) so I can check that one? I think they may be the wires on the top of the heater control's temperature sensor (the dial)....is that correct? I have searched on this but can't find the answer. Any help you can provide would be appreciated. Thanks again.
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1986 930, Instant G 3.6 Varioram Conversion, Cyntex chip, cams, solid lifters, custom exhaust, G50 trans, 22mm front and 29 mm rear, tarrett sway bars front and rear, strut tower brace, brembos, 18" turbo twist wheels |
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01-07-2017, 08:06 AM
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Join Date: Jun 2009
Location: Manhattan Beach, California. Factory Delivery-Original owner-Retired engineer
Posts: 5,238
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Sensor.
Quote:
auto heat. pm me as needed. Best, Gerry
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1986 911 Targa. Per Road and Track magazine: Only in L.A.: In the window of a bar in Hermosa Beach, California. "Happy Hour prices during all car chases." |
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01-07-2017, 08:47 AM
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Join Date: Oct 2006
Location: MYR S.C.
Posts: 17,321
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you can test it in the car. DO NOT connect the sensors or the arm to the flapper box.
in the pic above the arm is almost in the "heat on" position. the arm should keep going CCW until it hits the limit switch. the switch with the red and blk wires in power for the fans. as it is now, the switch contacts are open. press the switch and the contacts should close. test with meter. here is the link you want. auto heat- foot well blowers part deux.
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86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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01-09-2017, 03:55 AM
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1987 Porsche 911 Carrera
