ac compressor wont engage

[FrenchToasty]

I got your PM. I had no idea you had answered my question. If you want me (or anybody) to come back to a thread you need to QUOTE me so I get a notification. I can't go back to everybody's thread to see if there is a new post. I do a lot of things on here.

A pic would be more useful. Your sentence is a little flaky and I can't tell if you are talking about a black-yellow wire or a black wire and a yellow wire.

The 12V trigger for the clutch leaves the AC amplifier as a black-yellow wire, transits the 8-pin IJ1 connector on Pin 2 to a Lightgreen-black wire that goes all the way to the clutch via the engine harness.

Blue-white wires are the power circuit for the A/C system. one blue-white returns from the pressure switch to the AC amplifier through the same IJ1 connector the clutch trigger goes through.

This from my paper EWD, and my scanner is on loan and I don't know when the kid will bring it back. So I can't post it. My EWD is '99, but '99 and 2000 are usually twins except for DRLs.

That said, you are wasting time if you try to troubleshoot an A/C system without a set of gauges. At Harbor Freight with a coupon you can get a decent set for $60. It will pay for itself the first time you don't go to a shop. You need to know if there is pressure in the system. Leaks are much more common than electrical issues and I really don't have time to troubleshoot an empty system.

Having experience, almost always a issue with loss of charge or LP, hoses/seals (high side) are usually to blame

 

[OldManKamps]

I got your PM. I had no idea you had answered my question. If you want me (or anybody) to come back to a thread you need to QUOTE me so I get a notification. I can't go back to everybody's thread to see if there is a new post. I do a lot of things on here.

A pic would be more useful. Your sentence is a little flaky and I can't tell if you are talking about a black-yellow wire or a black wire and a yellow wire.

The 12V trigger for the clutch leaves the AC amplifier as a black-yellow wire, transits the 8-pin IJ1 connector on Pin 2 to a Lightgreen-black wire that goes all the way to the clutch via the engine harness.

Blue-white wires are the power circuit for the A/C system. one blue-white returns from the pressure switch to the AC amplifier through the same IJ1 connector the clutch trigger goes through.

This from my paper EWD, and my scanner is on loan and I don't know when the kid will bring it back. So I can't post it. My EWD is '99, but '99 and 2000 are usually twins except for DRLs.

That said, you are wasting time if you try to troubleshoot an A/C system without a set of gauges. At Harbor Freight with a coupon you can get a decent set for $60. It will pay for itself the first time you don't go to a shop. You need to know if there is pressure in the system. Leaks are much more common than electrical issues and I really don't have time to troubleshoot an empty system.

Oh okay!! I thought I quoted you.. sorry
Thanks for all that information! I was talking about a black wire and a yellow wire that go into a plug. I figured out from my friends parts truck that this is the wire that turns on the A/C when you turn the knob to defrost.
I'm not gonna bother with fixing that. So essentially the PO removed the whole cooling unit because of the evaporator leaking. I replaced the evaporator but the lines aren't attached yet because I want them all cleaned and I don't have a clip for the small line.

I wanted to figure out the electrical issue (blown fuse, stray wire) before I brought it to an A/C shop.

So right now, when I press A/C, the green light comes on but the engine RPMs don't change and I don't hear anything change at all in the engine bay. Is that because my A/C lines have no refrigerant? Is the pressure switch simply not allowing the clutch to activate? Should I charge the system and then try?

Also, will a gauge set allow me to do a leak and vacuum seal test?

Thanks Durk!!

Sent from my Nexus 5X using Tapatalk

 

[TheDurk]

Oh okay!! I thought I quoted you.. sorry
Thanks for all that information! I was talking about a black wire and a yellow wire that go into a plug. I figured out from my friends parts truck that this is the wire that turns on the A/C when you turn the knob to defrost.
I'm not gonna bother with fixing that. So essentially the PO removed the whole cooling unit because of the evaporator leaking. I replaced the evaporator but the lines aren't attached yet because I want them all cleaned and I don't have a clip for the small line.

I wanted to figure out the electrical issue (blown fuse, stray wire) before I brought it to an A/C shop.

So right now, when I press A/C, the green light comes on but the engine RPMs don't change and I don't hear anything change at all in the engine bay. Is that because my A/C lines have no refrigerant? Is the pressure switch simply not allowing the clutch to activate? Should I charge the system and then try?

Also, will a gauge set allow me to do a leak and vacuum seal test?

Thanks Durk!!

Sent from my Nexus 5X using Tapatalk

There are no solid black or yellow wires in the circuit. The digital system has those, but you said you have a manual. What makes you think they are part of the A/C?

Yeah, the pressure switch cuts the power to an empty system so the compressor will not run. Of course, if you blow a NEW fuse in that state, you can troubleshoot that, but otherwise there is nothing you can do until you put pressure in the system. You COULD jump the switch, but you have to fill it anyway, so what's the point?

To do a leak test, the gold standard is to evacuate the system with a vacuum pump, about $100 at HF, and use your gauges to see if it holds after a half hour. With the vacuum pump and a set of gauges, you can charge an empty system yourself, and what you save will pretty much pay for the tools...ok maybe two-thirds. Hopefully you can borrow a gram scale and digital thermometer from the kitchen. You have to do a fair amount of homework to learn how to do it right, but it pays dividends.

Don't listen to the A/C pros diss the HF stuff. If you use it only a few times a year, they work fine.

 

[IBallEngineer]

There are no solid black or yellow wires in the circuit. The digital system has those, but you said you have a manual. What makes you think they are part of the A/C?

Yeah, the pressure switch cuts the power to an empty system so the compressor will not run. Of course, if you blow a NEW fuse in that state, you can troubleshoot that, but otherwise there is nothing you can do until you put pressure in the system. You COULD jump the switch, but you have to fill it anyway, so what's the point?

To do a leak test, the gold standard is to evacuate the system with a vacuum pump, about $100 at HF, and use your gauges to see if it holds after a half hour. With the vacuum pump and a set of gauges, you can charge an empty system yourself, and what you save will pretty much pay for the tools...ok maybe two-thirds. Hopefully you can borrow a gram scale and digital thermometer from the kitchen. You have to do a fair amount of homework to learn how to do it right, but it pays dividends.

Don't listen to the A/C pros diss the HF stuff. If you use it only a few times a year, they work fine.

I diss the HF stuff all the time, but mainly if you are trying to use that crap as a professional. It's fine for one time or minimal use. Bought a nice looking battery terminal end crimper, used it, now it's done. Not really, but I would not expect it to live through every day use.

 

[OldManKamps]

There are no solid black or yellow wires in the circuit. The digital system has those, but you said you have a manual. What makes you think they are part of the A/C?

Yeah, the pressure switch cuts the power to an empty system so the compressor will not run. Of course, if you blow a NEW fuse in that state, you can troubleshoot that, but otherwise there is nothing you can do until you put pressure in the system. You COULD jump the switch, but you have to fill it anyway, so what's the point?

To do a leak test, the gold standard is to evacuate the system with a vacuum pump, about $100 at HF, and use your gauges to see if it holds after a half hour. With the vacuum pump and a set of gauges, you can charge an empty system yourself, and what you save will pretty much pay for the tools...ok maybe two-thirds. Hopefully you can borrow a gram scale and digital thermometer from the kitchen. You have to do a fair amount of homework to learn how to do it right, but it pays dividends.

Don't listen to the A/C pros diss the HF stuff. If you use it only a few times a year, they work fine.

Thanks a lot for all this information man! I really appreciate it!
Maybe I'm confused about digital vs. manual. My climate control is 2 nobs, 2 sliders, and an A/C button.

I'm gonna take the professional route as I have no need for A/C tools once this gets fixed haha

 

[TheDurk]

Thanks a lot for all this information man! I really appreciate it!
Maybe I'm confused about digital vs. manual. My climate control is 2 nobs, 2 sliders, and an A/C button.

I'm gonna take the professional route as I have no need for A/C tools once this gets fixed haha

Is one slider long for temp and one short for the fan? That's like the '99 manual. The digital has a digital readout window.

Maybe yours is like the 2001-2002 manual, that does have yellow and black wires. That EWD is here:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/057acman.pdf

Unfortunately, I don't have access to a 2000 EWD.

 

[OldManKamps]

Well, I guess maybe I was wrong. Sounds like yours is more like the 2001-2002 than the 1999. That does have solid yellow and black wires, but they aren't the clutch trigger either. Here is the EWD:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/systemci/057acman.pdf

The clutch trigger is white-green. The black and yellow go to the air mix servo.

Is the air mix servo the adjuster for face, face/feet, feet, feet/defrost, defrost?
The black and the yellow wire go into a small contact breadboard underneath the whole climate control unit and when i took it apart, it was obvious that those wires turned on the A/C when the knob was turned to defrost.

 

[TheDurk]

Is the air mix servo the adjuster for face, face/feet, feet, feet/defrost, defrost?
The black and the yellow wire go into a small contact breadboard underneath the whole climate control unit and when i took it apart, it was obvious that those wires turned on the A/C when the knob was turned to defrost.

Well, not really. The 'control box' aka A/C amplifier turns on the A/C and turns the air mix to defrost at the same time. You are confusing two effects for cause and effect.

From the EWD above:

AIR CONDITIONING OPERATION
When the blower SW is set to on, current from the HEATER fuse flows through the A.C fuse to TERMINAL 1 of the A/C dual
pressure SW to TERMINAL 2 to TERMINAL 3 of the A/C amplifier. The engine speed signal from engine control Module and
the evaporator temp. signal from the A/C thermistor are all supplied to the A/C amplifier. When the A/C SW is turned on, the
A/C SW on signal is sent to activate the A/C amplifier. Current flows from the A/C amplifier to the magnetic clutch, turning the
compressor on. The A/C operation is shut off when a signal indicating low evaporator temp., or abnormally high or low
refrigerant pressure, is supplied while the engine high speed signal exists. When one of these signals is received, the
amplifier shuts off the A/C operation.

Something similar happens on DEFROST, except the A/C button doesn't get pushed, you call Defrost and the air mix servo changes the air to go through the heater core and up to the window.

 

[birdhaus]

AC Clutch relay location 1999 4Runner SR5

I'm jumping on the thread in the hopes that someone can help me with my AC,
It has a full charge, but the clutch won't engage.
I have manual climate control and the fuse / relay Box under the hood has no markings for an AC clutch relay. I have read that the relay would maybe be in the passenger side kick panel, which I pulled, but can't ID an appropriate relay?

Photos available:
Client Area for /4runner/

 

[TheDurk]

I'm jumping on the thread in the hopes that someone can help me with my AC,
It has a full charge, but the clutch won't engage.
I have manual climate control and the fuse / relay Box under the hood has no markings for an AC clutch relay. I have read that the relay would maybe be in the passenger side kick panel, which I pulled, but can't ID an appropriate relay?

Photos available:
Client Area for /4runner/

Who said there was a clutch relay? That function is built into the "A/C Amplifier", the ECU for the HVAC system.

 

[birdhaus]

Yup, I read about relays in Gen 3's, and that led me down the rabbit hole.
Will run down AC amp.