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#1
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90 Honda AC Problem
My 90 Honda prelude Si's AC works Fine 1st thing in the morning, However
after about 15 minutes the red light on the AC switch comes on which indicates the compressor cut off. The AC will then not work the rest of the day. Red light will come on within 10 seconds after turning the AC on. HELP PLEASE! |
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#2
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The first thing I would check is the system pressures. The compressor
can be erratic (due to low pressure sensor) if the refrigerant charge is low. Professor www.telstar-electronics.com |
#3
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Your '90 Prelude has a compressor clutch slippage detection system. The red
light in the switch indicates one of two things: either the ac clutch IS slipping or, the detection system THINKS the ac clutch is slipping. The crank shaft pulleys delaminate on these occasionally, that could be the problem, or the compressor has developed a leak at the front seal. Here are some tips from Honda's own Service News from September '00 A/C Warning Light On: ’88–91 Prelude On ’88–91 Preludes, the red A/C warning light comes on when the speeds of the A/C compressor pulley and the crankshaft are different for more than 3 seconds. Here’s what can cause the speeds to differ, and how to repair the possible problems: Crankshaft pulley separation. On some models, a rubber insulator joins the hub and rim of the crankshaft pulley. If the bond fails between the insulator and the hub or rim, the hub turns with the crankshaft, but the rim slips on the insulator, making the A/C warning light come on. To check for this slippage, draw a line across the pulley. Start the engine, rev it up, then shut it off. Look at the line you drew on the pulley. If the marks across the hub and rim aren’t still lined up, replace the pulley. Compressor clutch oil seal leakage. On ’88–89 models, a leaking oil seal can contaminate the compressor clutch and cause it to slip, making the A/C warning light come on. Inspect the compressor clutch oil seal, and replace it if necessary (see S/B 88-038, A/C Compressor Front Seal Leakage, filed under Accessories). Compressor pick-up sensor. On ’90 models, a defective pick-up sensor can send a false signal to the compressor control unit, making the A/C warning light come on. Check for a defective pick-up sensor, and replace it if necessary (see S/B 90-019, A/C Compressor Pick-up Sensor Set Replacement, filed under Accessories). Compressor control unit. If the A/C warning light is on without any of the above problems, use an 8X magnifier to inspect the solder joints inside the compressor control unit. If any of the solder joints are cracked, clean and resolder the printed circuit board, or replace the compressor control unit. jonman wrote: > My 90 Honda prelude Si's AC works Fine 1st thing in the morning, However > after about 15 minutes the red light on the AC switch comes on which > indicates the compressor cut off. The AC will then not work the rest of > the day. Red light will come on within 10 seconds after turning the AC > on. > > HELP PLEASE! -- Tp, -------- __o ----- -\<. -------- __o --- ( )/ ( ) ---- -\<. -------------------- ( )/ ( ) ----------------------------------------- No Lawsuit Ever Fixed A Moron... |
#4
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#5
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Thanks guys, yall rock.
Have narrowed the problem to heat. have the car in my shop, which is airconditioned and the compressor cuts off when the engine gets up to running temp. also noticed that the cooling fan relay is gone. Weird. I didn't take it. I Know its not the pressure switch, AC relay 1 or 2, or freon pressure system is fully charged. When the engine cools its fine. is there a temp sensor or switch that I can't find and if so where would it be. |
#6
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"jonman" > wrote in message
lkaboutautos.com... > Thanks guys, yall rock. > Have narrowed the problem to heat. have the car in my shop, which is > airconditioned and the compressor cuts off when the engine gets up to > running temp. also noticed that the cooling fan relay is gone. Weird. I > didn't take it. I Know its not the pressure switch, AC relay 1 or 2, or > freon pressure system is fully charged. When the engine cools its fine. > is there a temp sensor or switch that I can't find and if so where would > it be. Really weird that the condensor fan relay is missing. I don't remember where it is mounted, but assume that you only have half the fans running (rad) that should be when the AC is on, unless somebody rewired things? As TomP speculated, I actually experienced the pick-up sensor failure in my 90 Si ALB after 8 years. It was intermittent, but usually would only fail after work (sitting in the HOT summer sun all day), but hardly ever in the morning. Try measuring the sensor resistance (engine & key off) when hot at the 2 pin connector near the compressor, or just use needles to pierce the wires (I found the 2 sensor wires--white(gnd) and green(signal)-- in the spiral wrap jacket running across the radiator below the bumper-easier for me than trying to get my hands on the connector). My bypass circuit uses the ECU "AC Request" signal, shifts it to 12V through a PNP transitor and passes it to the coils of compressor clutch relays A and B. Slipping/stalled sensing is disabled, but most cars don't have it anyway. Here's what I reported to some others 3 years ago on the same subject : Hi, I had this same problem on my '90 Prelude SI. Honda had a Service Bulletin against a group of Sanden AC compressors (Bulletin No 90-019 July 27, 1990). My symptons were that the AC compressor clutch would cut out after about 1-2 seconds of running and the red error LED would come on in the AC switch. After pushing the AC switch on/off three times, the speed sensor module completely locks out the compressor clutch until the ignition is turned off. The bulletin listed normal sensor impedance as 365-445 ohms at 68 degF., but I think the manual had the numbers a little higher. When my sensor was intermittent, it would read as an open when failing. As you probably found out, you can't replace the sensor without removing the compressor (ac hoses, splash panel, recharge R-12). And you can't simply short across the sensor since the control module "counts" the revolutions of the compressor vs the engine to make sure the compressor isn't stalled. I built a simple one transistor (with bias resistors and protection diodes) circuit to replace the sensor module ('90 was mounted up behind the glove box on the side kick panel under another warning module (seat belt??). It worked for me for another year while I had the car and was still working for the next owner. The same design worked for another lude owner (I think '89) who built the circuit in June 2000. I've scanned the service bulletin and my hand drawn circuit and can post it here or send it to you. All of the parts are readily available (Radio Shack, etc). The only tricky part was finding pins for the module mating connector. I wanted to maintain the 12 pin harness connector in case I ever had to reinstall the original module (a 24 pin ic with a slew of transistors, etc.). I found a connector with the exact pins (but not the right shape connector) at a local electronics part store and just taped the new circuit's wires in place after mating them to the harness. J. |
#7
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J.
Awesome feedback. If it is not to much to ask could you email the circuit schematic to me, assuming you still have it to . You'd be such a hero in my book. Thanks Jon |
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