Honda Prelude Compressor AC A/C Warning Light Red Problem
Tommy
This is my 2nd post with different subject heading. Hope someone
will read and help !
My 89 prelude's ac stop working everytime when the car get hot. The
shop use a manifold gauge and recharge refrigant(Less than was 1/2 lbs
needed). No leaks waw found. Low pressure switch seems working.
The compressor Thermal protector seems working right. But when
measuring resistance across the Pickup / Speed sensor circuit, I got
618
ohms(car was hot and the ac quit). After let it cool down a bit to
about 595
ohms, the ac works again. It will quit again when it get hot and the
compressor clutch cycle.
The Pickup sensor resistance were measure directly from the
compressor connector behind the condensor fan. The manual said max.
should be 600 ohms, therefore I assume sometime went wrong with the
pickup sensor.
From this newsgroup, someone mention they had a transistor
circuit to replace/bypass the sensor.
Would anyone still has the circuit design sending me information on
how to
do it? Some tips/instructions will be a plus.
thanks in advance,
Tommy Fung
George Macdonald
With all due respect your post is a little muddled which may explain the
lack of a previous response. First you talk of the thermal protector which
AFAIK is an on/off switch which is fairly easily replaced on some
compressors... but then you indicate that it is OK. Then you talk of the
"pickup/speed sensor" giving a high resistance. I don't have a service
manual for your car but have several Honda manuals for other cars of that
era and there is no mention of a "pickup sensor" in any of them.
If you don't get a response here again you might try the Q&A forum at
<www.aircondition.com> where all the umm, air heads hang out.
Rgds, George Macdonald
"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??
J.
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
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 if they even do that anymore). 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 can try scanning the service bulletin and the hand drawn circuit and 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.
Jack
Tommy <tommy...@cybermail.net> wrote in message
news:cf1de428.02071...@posting.google.com...
Tommy
I believe you have the answer I'm looking for.
Would you please email me the circuit information ?
Thanks in Advance,
tommy
P.S. Instructions on how to connect the new circuit to the factory
circuit will be a great help.
"J." <J...@nobody.com> wrote in message news:<IZEY8.160257$Im2.7...@bin2.nnrp.aus1.giganews.com>...
Mike Wax
perhaps you can clue me in on a similar situation with my car. it is an 89
Prelude and the compressor clutch won't engage. i push the A/C button on the
dash and nothing happens. I connected the compressor wire to the batery and
the clutch engaged, but there was no sign of bubles in the sight glass and
no cooling effect inside. could this be the same problem of the speed
sensor?
>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
what about just putting a resistor 400 ohms across the sensor?
thanx, mike wax
George Macdonald
wrote:
>Hello,
>
>perhaps you can clue me in on a similar situation with my car. it is an 89
>Prelude and the compressor clutch won't engage. i push the A/C button on the
>dash and nothing happens. I connected the compressor wire to the batery and
>the clutch engaged, but there was no sign of bubles in the sight glass and
>no cooling effect inside. could this be the same problem of the speed
>sensor?
Are you sure the compressor is being turned at proper speed. There was a
reported problem with some models around that time where the rubber of the
harmonic damper on the crankshaft pulley would tear and allow the rim of
the pulley to "float". This was mentioned at Tech2Tech.net - unfortunately
no longer available - and of course it affected all belts. Did your bypass
allow the fans to come on? They're needed to condense the refrigerant.
Mike Wax
>Are you sure the compressor is being turned at proper speed. There was a
>reported problem with some models around that time where the rubber of the
>harmonic damper on the crankshaft pulley would tear and allow the rim of
>the pulley to "float". This was mentioned at Tech2Tech.net - unfortunately
>no longer available - and of course it affected all belts. Did your bypass
>allow the fans to come on? They're needed to condense the refrigerant.
no, it would not switch the fans, but they were already on because the
engine was warmed up. and i got my info wrong. the car is an 87 Prelude, not
89. the belts are all OK.
mike
J.
It doesn't sound like the same problem and I'm not sure if Honda put the
sensor on the '87 Prelude ('87 was the last of its generation I believe - I
previously had an '84 lude before the '90 SI). I think the "sensored"
compressor had a 4 wire connector (2 pins for the sensor, 1 pin for sensing
clutch power and 1 pin for supplying clutch power through the compressor
thermal protect switch).
If the compressor clutch is truly engaged and you don't see any bubbles in
the sight glass, sounds like you're out of Freon. Also, some years of
Preludes had just one radiator fan come on normally due to coolant temp,
while both would be forced on while the compressor is engaged.
If you do have an A/C sensor and module, just hooking a resistor across the
input to the module will not work since the original module counts the
compressor shaft rotations (sort of like how ABS counts axle revolutions)
and compares it to the engine/distributor rpms.
J.
Mike Wax <isawa...@toughguy.net> wrote in message
news:%qNZ8.584856$cQ3.65473@sccrnsc01...
Mike Wax
>compressor had a 4 wire connector (2 pins for the sensor, 1 pin for sensing
>clutch power and 1 pin for supplying clutch power through the compressor
>thermal protect switch).
>
reply.
mike wax