1995 4Runner Air condition problem

Recently purchased a 95 SR5 4runner(last week...); A/C charged by car
dealer at purchase. Problem is during day blows cold for about five
minutes, than blows warn (not extreme hot but uncomfortable warm. However
at night if I take it out for drive will freeze you out and stays cold.The
obvious I know is drive at night, but would like an answer if someone has
had this happen in a Toyota. Thanks!

john711111 wrote:[color=blue]
> Recently purchased a 95 SR5 4runner(last week...); A/C charged by car
> dealer at purchase. Problem is during day blows cold for about five
> minutes, than blows warn (not extreme hot but uncomfortable warm. However
> at night if I take it out for drive will freeze you out and stays cold.The
> obvious I know is drive at night, but would like an answer if someone has
> had this happen in a Toyota. Thanks![/color]

On my '94 there is a thermister (sp?) under the right side of the dash
near the A/C amplifier board, and tied into it's circuit. As I
understand it it's supposed to turn the A/C on and off in response to
engine load, speed, temperature, etc. You might try making a slight
adjustment of the amplifier board adjustment knob to see where it gets
you (you can always turn it back).

Sorry I don't have full information about how the thermister affects
the circuit or how to test it, but it's probably worth a try.

dennis
in nca

thanks for the reply makes as much sense as anything plus cheap test to
try. I think that is called thermal resistor but I may be calling it
wrong name. any other suggestions appreciated.

On 20 Jun 2006 08:49:26 -0700, "rigger" <dgrup@aol.com> wrote:[color=blue]
>john711111 wrote:[/color]
[color=blue][color=green]
>> Recently purchased a 95 SR5 4runner(last week...); A/C charged by car
>> dealer at purchase. Problem is during day blows cold for about five
>> minutes, than blows warn (not extreme hot but uncomfortable warm. However
>> at night if I take it out for drive will freeze you out and stays cold.The
>> obvious I know is drive at night, but would like an answer if someone has
>> had this happen in a Toyota. Thanks![/color]
>
>On my '94 there is a thermister (sp?) under the right side of the dash
>near the A/C amplifier board, and tied into it's circuit. As I
>understand it it's supposed to turn the A/C on and off in response to
>engine load, speed, temperature, etc. You might try making a slight
>adjustment of the amplifier board adjustment knob to see where it gets
>you (you can always turn it back).
>
>Sorry I don't have full information about how the thermister affects
>the circuit or how to test it, but it's probably worth a try.
>
>dennis
>in nca[/color]

Egad, is EVERYONE following me over here from r.c.metalworking? ;-)

The thermistor is connected to the AC Amplifier and is supposed to
be in the heater box on the evaporator core, so it can sense when the
core is icing up and have the AC Amplifier module cut off the
compressor for a defrost period.

If the evap core ices up it won't blow hot, it'll stop blowing at
all as the airflow is progressively restricted by the ice. Left
unchecked, you can build up a big block of ice in there.

The other main function of the AC Amplifier module is to watch the
rotation of the compressor crankshaft (via a sensor on the compressor)
versus engine RPM - if the compressor has internal problems and locks
up, the AC clutch will not slip. The fan belt will slip instead and
either break and leave you stranded, or catch fire and leave you with
a much bigger problem...

If the AC Amplifier thinks the compressor has locked up, it cuts off
the clutch power and starts blinking the blue dashboard AC button lamp
as an alarm indicator.

If the AC cuts off and blows hot during the day but works fine at
night, I'm betting it's overcharged with refrigerant and the AC System
has a high-limit pressure switch that is tripping. At night it gets
cool enough for the high-side pressure to drop past the 'Reset' point,
and it is cool enough not to trip it during operation.

Or this is a R-12 to R-134 conversion car, and they didn't change
the high-side switch to the R-134 version. R-134 normal operating
high-side pressures are much higher than R-12, and the wrong switch
would trip during normal use.

--<< Bruce >>--

Bruuuuce!!, thanks for the info, best descript of amplifer board i have
read. Even my chilton book just shows location and says to remove -detach
wiring harness -to install reattach wiring harness. Nothing goes into
detail, my guess they don't won't us touching the d.... thing. As far as
the adjustment knob sticking out of the top, what is it actually
controlling? In other words, does clockwise or counter clockwise increase
or decrease cooling range or compressor on/off points or something
entirely diffrent. Thanks for the enlightment to everyone. ***This is the
first 4runner(95 w/117K) miles for me, long time Toyota fan (current 99
Camary 150K miles and past proud owner of 85 Celica GT with thats right
279K miles and still running when sold)
** You got answers I got questions!**
My field of advice is finance and exwives will trade tip for tip!!:)

john711111 wrote:[color=blue]
> Bruuuuce!!, thanks for the info, best descript of amplifer board i have
> read. Even my chilton book just shows location and says to remove -detach
> wiring harness -to install reattach wiring harness. Nothing goes into
> detail, my guess they don't won't us touching the d.... thing. As far as
> the adjustment knob sticking out of the top, what is it actually
> controlling? In other words, does clockwise or counter clockwise increase
> or decrease cooling range or compressor on/off points or something
> entirely diffrent. Thanks for the enlightment to everyone. ***This is the
> first 4runner(95 w/117K) miles for me, long time Toyota fan (current 99
> Camary 150K miles and past proud owner of 85 Celica GT with thats right
> 279K miles and still running when sold)
> ** You got answers I got questions!**
> My field of advice is finance and exwives will trade tip for tip!!:)[/color]

Hi John. I hope Bruce chimes in on this one as it seems he REALLY
knows what he's talking about. But in any case I'll mention the
amplifier board adjustment is used for setting the
idle/air-conditioning point. So that by setting the amplifier board
correctly to your idle speed you'll still get A/C operation but slow
down below that point and the A/C will cut off before you stall.

Or so I've read. Good luck.

dennis
in nca

john711111 wrote:[color=blue]
> Bruuuuce!!, thanks for the info, best descript of amplifer board i have
> read. Even my chilton book just shows location and says to remove -detach
> wiring harness -to install reattach wiring harness. Nothing goes into
> detail, my guess they don't won't us touching the d.... thing. As far as
> the adjustment knob sticking out of the top, what is it actually
> controlling? In other words, does clockwise or counter clockwise increase
> or decrease cooling range or compressor on/off points or something
> entirely diffrent. Thanks for the enlightment to everyone. ***This is the
> first 4runner(95 w/117K) miles for me, long time Toyota fan (current 99
> Camary 150K miles and past proud owner of 85 Celica GT with thats right
> 279K miles and still running when sold)
> ** You got answers I got questions!**
> My field of advice is finance and exwives will trade tip for tip!!:)[/color]

Hi John. I hope Bruce chimes in on this one as it seems he REALLY
knows what he's talking about. But in any case I'll mention the
amplifier board adjustment is used for setting the
idle/air-conditioning point. So that by setting the amplifier board
correctly to your idle speed you'll still get A/C operation but slow
down below that point and the A/C will cut off before you stall.

Or so I've read. Good luck.

dennis
in nca

On Wed, 21 Jun 2006 08:53:01 -0400, "john711111"
<john711111@nospam.yahoo.com> wrote:
[color=blue]
> As far as
>the adjustment knob sticking out of the top, what is it actually
>controlling? In other words, does clockwise or counter clockwise increase
>or decrease cooling range or compressor on/off points or something
>entirely diffrent.[/color]

I'm pretty sure the knob is the trip point setting for the
thermistor defrost sensor - like rigger said, make a mark where you
found it set from the factory, and tweak away. But it shouldn't take
much. (I'll bet it's in the factory repair manual, but I'd have to
find where mine has gotten to...)

Get an instant-reading pocket dial thermometer from the Chef
Supplies section at your market, and stick it in the main AC outlet
ducts. Then you can see the temperatures that the compressor is
cutting in and out at. If the output air is getting down into the
high thirties, that's too cold - the core itself could be below 32 and
starting to ice up.

--<< Bruce >>--

Info tip I found:
<http://www.findarticles.com/p/articles/mi_qa3828/is_200206/ai_n9092114>

just right click -hightlight & copy and paste in your address bar to open.

John I think you are all barking up the wrong tree, the symptoms you are
describing are moisture in the system the remedy is to purge the system
change the receiver drier vacuum down and regas.
Joe


"john711111" <john711111@nospam.yahoo.com> wrote in message
news:f8828d7015eb3ff1dd9a29160ba1e062@localhost.talkaboutautos.com...[color=blue]
> Recently purchased a 95 SR5 4runner(last week...); A/C charged by car
> dealer at purchase. Problem is during day blows cold for about five
> minutes, than blows warn (not extreme hot but uncomfortable warm. However
> at night if I take it out for drive will freeze you out and stays cold.The
> obvious I know is drive at night, but would like an answer if someone has
> had this happen in a Toyota. Thanks!
>
>[/color]

thanks for the help, i still don't understand the day/night diffrence. If
the problem is moisture how does that affect the A/C, summer temp here
between day and night is only varying by 10-12 degrees. thanks to all!

"You got answers, I got questions!"

the temp difference is enough to condense moisture on the TX valve blocking
off gas flow then melting and gas flows again hence the temp increase. Or
over charged and the compressor is going out on over pressure, these are the
two most common reasons for your symptoms and both require gauges to detect.
Joe


"john711111" <john711111@nospam.yahoo.com> wrote in message
news:3f5de1b8831eed11205f323202d10958@localhost.talkaboutautos.com...[color=blue]
> thanks for the help, i still don't understand the day/night diffrence. If
> the problem is moisture how does that affect the A/C, summer temp here
> between day and night is only varying by 10-12 degrees. thanks to all!
>
> "You got answers, I got questions!"
>[/color]

"john711111" <john711111@nospam.yahoo.com> wrote in message news:f8828d7015eb3ff1dd9a29160ba1e062@localhost.talkaboutautos.com...[color=blue]
> Recently purchased a 95 SR5 4runner(last week...); A/C charged by car
> dealer at purchase. Problem is during day blows cold for about five
> minutes, than blows warn (not extreme hot but uncomfortable warm. However
> at night if I take it out for drive will freeze you out and stays cold.The
> obvious I know is drive at night, but would like an answer if someone has
> had this happen in a Toyota. Thanks!
>
>[/color]



It's only been a week? Take it back to the dealer they need to fix there mistake.

Chances are pretty good there is a refrigerant leak that needs to be fixed. If they
just charged a known leaking system (low=leaking) and told you the a/c was ok I would be pissed.
That most likely was done intentionally to avoid repairing the problem and get you out the door.

If your a/c system has a sight glass and you see bubbles with the compressor running
that don't clear up its low on refrigerant. If the a/c works ok @ highway speeds only the
engine cooling fan fluid coupling or something blocking the air flow across the condenser coil.

The symptoms you have sound like its low on refrigerant from a leak that will cause it to fail
when a little more has leaked out. (just a guess)

GL
Dan

BTW:) Its not the thermister or a wet system