1993 FZJ80 - AC electrical issue & not working (Compressor in good condition & system not leaking). (2 Viewers)

[TankTheLC]

Hey all. I took my truck into my local firestone today to have the freon checked because a month ago the AC just suddenly stopped working. They put a power probe (edit) on the system to test the compressor and confirmed it was in good shape, they ran dye through the system with no apparent leaks, and had them recharge the system with R134A. They confirmed that the recharge to the proper levels of refrigerant. The technician stated he traced the issue to the A/C Cut Relay but they don't take the dash apart so this is where they stopped - Ok cool. I came home pulled the relay and called the local toyota to order another (It was a weird shape so I couldn't use one from the driver's side kick panel). I attempted to bridge pins 3 and 4 to attempt to see if the AC would start working and to no avail. I have a fluke multimeter (Albeit I'm a novice) and a 1993 Toyota Land Cruiser Electrical Wiring Diagram. If this relay doesn't repair the system it would appear maybe the downstream components labeled A1 - A/C Magnetic Clutch or W4 Water Temp SW could be culprits but there isn't a ton of information here on where those are located. I've got all the tools I need and the patience to measure with the multimeter what is needed to resolve this - Help guide me through troubleshooting this issue.

Additional Information: All the dash lights work including the AC - When the AC is switched on there isn't a change in blower power (Just blowing ambient air). I can't hear the compressor kicking on or a relay clicking. The truck is not overheating and the cooling system was completely overhauled in August/September.

Resources I've used thus far beyond the manuals I own:
AC help desperately needed
A/C Clutch not Engaging

The document shared with me by Firestone of the culprit after testing the system:

What I'm looking at on my current truck:

 

[wfd175]

I would start at the blower speed control relay . Btw Did they flush prior to putting in the 134a? Or is it a post 5/93 manufactured r134a system . Mine is a 4/93 and I switched it over to a R134 from a R12. Replaced every component . Works great .

 

[TankTheLC]

I would start at the blower speed control relay . Btw Did they flush prior to putting in the 134a? Or is it a post 5/93 manufactured r134a system . Mine is a 4/93 and I switched it over to a R134 from a R12. Replaced every component . Works great .

Post 5/93 manufactured 93 fzj80 all components were tested to be good in the actual system. Why do you say the blower speed control relay? All the blower speeds work - how should I test it?

 

[wfd175]

i misunderstood wen you referenced blower power not changing when you hit the ac button.
I did have another non Toyota vehicle that the blower relay went out and not even the ac light on the push button wouldn't lite up. I swapped the blower relay and all was good. If your getting ac lights on the push button, I'd lean towards the ac compressor pressure switch by the drier, or something is wrong with the mag ac clutch. I'm not familiar with the power pro tester. He hardest working part on the whole system is the compressor and clutch. It's a big ask to engage and disengage at all variations of rpms is why I say that. I had a bad compressor on mine so I swapped out the compressor with a new clutch. Along with consensor, Evap, pressure switch, drier, o rings (now green) and expansion valve because of age and I was heading to the Kokopelli in August and didn't want any issues. Filled with 134. All diy except the flush. Can the pressure switch be jumped to quickly turn the compressor on? Seems like should be.

 

[TankTheLC]

i misunderstood wen you referenced blower power not changing when you hit the ac button.
I did have another non Toyota vehicle that the blower relay went out and not even the ac light on the push button wouldn't lite up. I swapped the blower relay and all was good. If your getting ac lights on the push button, I'd lean towards the ac compressor pressure switch by the drier, or something is wrong with the mag ac clutch. I'm not familiar with the power pro tester. He hardest working part on the whole system is the compressor and clutch. It's a big ask to engage and disengage at all variations of rpms is why I say that. I had a bad compressor on mine so I swapped out the compressor with a new clutch. Along with consensor, Evap, pressure switch, drier, o rings (now green) and expansion valve because of age and I was heading to the Kokopelli in August and didn't want any issues. Filled with 134. All diy except the flush. Can the pressure switch be jumped to quickly turn the compressor on? Seems like should be.

From what I was told by the AC tech the power pro was used to confirm the compressor was in proper order. I did go out to check that the AC light was on and I can confirm it is - I’ll pick up the relay tomorrow but where do I go from here if that isn’t it?

Edit: To rule out something simple I did confirm both plugs on the back of the hvac controls were plugged in and I did reseat them to confirm they were clicked in.

 

[wfd175]

I google searched for anything called a power pro a/c diagnostic tool. I was curious what any shop could do beyond environmentalally friendly flushing , emptying, refilling and pressure checking and multimeter checking.

I didn't find anything called a power pro or any machines that could somehow check a compressor without the compressor cycling. So I wonder if they just did a leak, fill and pressure check? I'm not sure if without the compressor clutch engaged using just the flow or pressure difference on the high and low side ports on the compressor manifold if a test could measure if the compressor was still good.

When I removed my compressor, it felt and I could hear it was doing "something" when I turned it. When I got the new one, there was much more resistance and a definitive air hissing noise.

I knew my compressor was bad because the clutch was continuously engaged, but the system wasn't getting up to pressure on the high side. While diagnosing , the clutch disengaged and wouldn't re -engage. With any new compressor, the system should be flushed prior to installing the new one. A good flush isn't hooking it to a machine and flushing. I took mine to the shop for a half ass flush because r12 isn't as friendly as 134 and I wanted as much out of the system prior taking apart.

A good complete flush is breaking all the connections and flushing each component and tube. I first took out the condenser, there was a ton of crud in it, I then decided I if the evaporator has all this crud, it did. Inside and out. I then decided, I'll spend the $ and replace all diy and refill.

Btw The condenser on the 4/93 is a little wider than a 5/93 and beyond. It was also the most expensive denso component in the whole cleanse and all component swap .

Have you looked at the compressor while the ac was "on" to determine if the clutch was engaged?

Do you have a copy of the Fsm?

 

[TankTheLC]

I google searched for anything called a power pro a/c diagnostic tool. I was curious what any shop could do beyond environmentalally friendly flushing , emptying, refilling and pressure checking and multimeter checking.

I didn't find anything called a power pro or any machines that could somehow check a compressor without the compressor cycling. So I wonder if they just did a leak, fill and pressure check? I'm not sure if without the compressor clutch engaged using just the flow or pressure difference on the high and low side ports on the compressor manifold if a test could measure if the compressor was still good.

When I removed my compressor, it felt and I could hear it was doing "something" when I turned it. When I got the new one, there was much more resistance and a definitive air hissing noise.

I knew my compressor was bad because the clutch was continuously engaged, but the system wasn't getting up to pressure on the high side. While diagnosing , the clutch disengaged and wouldn't re -engage. With any new compressor, the system should be flushed prior to installing the new one. A good flush isn't hooking it to a machine and flushing. I took mine to the shop for a half ass flush because r12 isn't as friendly as 134 and I wanted as much out of the system prior taking apart.

A good complete flush is breaking all the connections and flushing each component and tube. I first took out the condenser, there was a ton of crud in it, I then decided I if the evaporator has all this crud, it did. Inside and out. I then decided, I'll spend the $ and replace all diy and refill.

Btw The condenser on the 4/93 is a little wider than a 5/93 and beyond. It was also the most expensive denso component in the whole cleanse and all component swap .

Have you looked at the compressor while the ac was "on" to determine if the clutch was engaged?

Do you have a copy of the Fsm?

My apologies the tool is actually called a power PROBE - Wow I have no idea how I messed that up so much.

I do have a copy of the 1993 Toyota Land Cruiser FSM.

I was told the compressor when on the power probe functioned exactly how it should and the issue is the compressor is NOT getting the power. I have not heard/me the clutch engaging and stopping but I haven't looked for it in a bit - I don't know if it work spin if the compressor wasn't getting power (I'm doubtful). The refrigerant was not an issue before as the AC blew colder than any of my other cars. The shop did confirm the r134A was evacuated with the machine and recharged with R134A. They did inspect my condenser and said it was in good shape and not leaking. The entire AC system was overhauled by the PO at an unknown mileage so its unlikely I'm working with 100% original components but bits and pieces. I'll record what happens when the AC button is on while the electronics are all hooked up and share what I am seeing.

Edit: I did want to share I don't know if its related or not but the recirc led light does not work in either orientation of the button.

Video of 2 minutes of the AC Button being on & the clutch not engaging is linked below. I can only presume this is because power isn't going to the compressor if the tech confirmed the compressor was in good working order (I have no reason to distrust the techs diagnosis using the power probe).

 

[wfd175]

Jumper the pressure switch (plug) by the ac drier for a quick second to see if the compressor clutch engages.

 

[TankTheLC]

Jumper the pressure switch (plug) by the ac drier for a quick second to see if the compressor clutch engages.

I've located that on the schematic - I'll give it one shot tonight locating it to have some direction for feedback on where to go next.

Update: I jumped pins 1 & 4 on the 2 wire 4 pin plug A3 Black (AC Pressure SW - A3 on schematic) and the compressor clutch did not engage. I only jumped and allowed contact for 2-3 seconds at a time 3 times with no activation or immediate signs of contact. (The wet material is dielectric grease not water intrusion).

Looking at the original schematic I shared - if the relay I get tomorrow doesn't activate the system (Starting to look unlikely but we'll see) the downstream components from that are W4 Water Temp. Switch (For A.C) located on the valve cover somewhere according to the schematic. Its a 2 pin connector to a switch I might be able to jump and see if the switch has failed. If you have any imput or direction from here I'd really appreciate it from anyone and I really appreciate @wfd175 helping me out. If someone is handy with electronics and could guide me through testing the A/C Amplifier I might be able to test where the signal is being lost easier but so far above is the direction I am going.

 

[wfd175]

I looked up the power probe test on a compressor. If they did that and the clutch engaged I'm still leaning towards the fan control first . if it's not that, Then the pressure switch being replaced. Lastly swap the compressor compressor and clutch. The first two parts are cheap the last is a nut.

 

[TankTheLC]

I looked up the power probe test on a compressor. If they did that and the clutch engaged I'm still leaning towards the fan control first . if it's not that, Then the pressure switch being replaced. Lastly swap the compressor compressor and clutch. The first two parts are cheap the last is a nut.

I appreciate the input - I'm not trying to blindly throw money at it and I didn't mind grabbing the 2nd relay from Mr T because it was only $20 and I don't mind a spare. Jumping the pressure switch proved to not resolve the issue (In the edit on post #9). The Blower Speed Control Relay B6 doesn't appear to be an issue but I don't mind taking it off and testing it use the multimeter. The compressor and clutch were already proven to work - if the compressor isn't getting power it doesn't make sense to replace it. When my multimeter fuses get here on Sunday I will hopefully be able to confirm the compressor is NOT getting power but for now I am just relaying information given to me by the tech. I really think somewhere in this circuit something is breaking the continuity and preventing the compressor from getting power but at this point its just speculation.

 

[wfd175]

Blower speed control relay in the fsm.
I hope you figure it out. Chasing electric issues as you know is a pain. We’re of course we are putting 100% confidence in the shops compressor engaging report at this point. I don’t have my fsm at the house and seeing it in the ipad even with glasses is difficult So I can’t trace the wiring diagram to see if there’s a relay between the downstream connection to the ac clutch from the pressure switch which engages the clutch as necessary to build pressure .
Your issue is odd. I read every post prior to the conversion to 134. Your issue is unique because of the info received from the shop, your ac button is working , your recirc button isn’t functioning and fan speed control is working. What makes the most sense is the compressor clutch is actually bad, or went bad like mine did mid ac issue diagnosis. My compressor went out because the clutch was stuck and it wore out the compressor continuously running a little low of R12.

 

[ChaseTruck]

Nothing more fun than electron chasing... that said, maybe I missed it: have you done any measurements along the circuit to determine whether there is power/ground where it should be, and where do you lose it?

 

[TankTheLC]

Blower speed control relay in the fsm.
I hope you figure it out. Chasing electric issues as you know is a pain. We’re of course we are putting 100% confidence in the shops compressor engaging report at this point. I don’t have my fsm at the house and seeing it in the ipad even with glasses is difficult So I can’t trace the wiring diagram to see if there’s a relay between the downstream connection to the ac clutch from the pressure switch which engages the clutch as necessary to build pressure .
Your issue is odd. I read every post prior to the conversion to 134. Your issue is unique because of the info received from the shop, your ac button is working , your recirc button isn’t functioning and fan speed control is working. What makes the most sense is the compressor clutch is actually bad, or went bad like mine did mid ac issue diagnosis. My compressor went out because the clutch was stuck and it wore out the compressor continuously running a little low of R12.

It is weird, I will hopefully be able to test the compressor tomorrow to make sure it gets power and also test that the clutch engages when power is applied. More to follow.

Nothing more fun than electron chasing... that said, maybe I missed it: have you done any measurements along the circuit to determine whether there is power/ground where it should be, and where do you lose it?

I have no, I am waiting for my fuses from Amazon for my fluke to roll in tomorrow - more to follow.

 

[TankTheLC]

Ok Electrical Update:

Here are the numbers measured:

• Continuity test of AC Compressor unplugged from the car: 0.002 (Beeped - continuity test good)
• Resistance test of AC Compressor unplugged from the car: 3.7Ω
• Voltage test of AC Compressor with pigtail plugged into the car: 0.00V DC
• Voltage test of the AC car harness side (Female) with black lead connected to battery: 0.425V DC

Additionally I did find that the male harness (Compressor Side) was broken and placed ontop of the airbox - This may have to do with power delivery to the AC Compressor but not sure how to go about replacing this harness.

My questions are:

• How do I fix the pigtail situation or is another compressor purchase warranted?
• Is the voltage measured at the compressor the correct voltage expected to be delivered to the compressor? It seemed quite low so it would appear the compressor isn't getting the power it needs and means further troubleshooting upstream is warranted.
• The video showing the AC Clutch engaging - Is it engaging properly or is something worn out causing it to kind of pull in the pulley?

Evidence of Test & Clutch Engaging Below:

Here is a video showing the clutch engaging when connected to the battery using jumper leads:


Continuity Test using red lead on power pigtail and black lead on grounded screw:

Resistance Test using red lead on power pigtail and black lead on grounded screw:

Voltage test with the power pigtail plugged into the compressor and the black lead connected to ground screw while truck is on & AC button is on:

Voltage test with the female car side plug harness and the black lead connected to the battery:

This was conveniently placed on top of the airbox and is the male side of the plug that attached to the AC Compressor:

 

[TankTheLC]

Another update figured I’d also run a test on both the relay and the fuse (I’m not as familiar with this testing so if I did something wrong don’t hesitate to correct me so we’re working with the right numbers).

Here are the numbers measured on the relay & fuse panel fuse:

• Resistance test of the A14 AC Cut Relay: 0.L Ω (I don't believe the circuit is being closed when power is applied)
• Continuity test of the A14 AC Cut Relay: 0.L Ω (I don't believe the circuit is being closed when power is applied)
• Resistance test of the A14 AC Cut Relay 1 & 2 side: 0.00Ω
• Resistance test of the A14 AC Cut Relay 3 & 4 side: 69.6Ω

Relay connected to battery both continuity and resistance read:

Resistance on the switch side of the relay with no power:

Resistance on magnet side of the relay with no power.

When power was applied the relay did click audibly and I could feel it but I know that doesn’t mean its working so I ran the test.

Additionally I also checked the voltage going across the fuse which fluctuated heavily:

 

[TankTheLC]

Can anyone confirm the voltage that should be coming to the ac compressor ? I got the new relay in and still not engaging. I’ve got numbers above but not sure what to do now.

 

[1972FJ55]

Can anyone confirm the voltage that should be coming to the ac compressor ? I got the new relay in and still not engaging. I’ve got numbers above but not sure what to do now.

The compressor coil needs a full 12 volts to operate without allowing the clutch to slip.

 

[TankTheLC]

The compressor coil needs a full 12 volts to operate without allowing the clutch to slip.

Thank you so much!

 

[TankTheLC]

Big Update!

Well I figured it out - the equation isn't solved yet but I have power! I started just going over the entire system and took apart the AC Climate Control box - Low & behold there is a little switch in there that is flipped to AUTO - I think thats not right I don't have an Auto AC truck - flip it back and jump the the damaged harness to see the clutch spinning when starting the car. Ironically the led for the Recirc also works now so that appears to have been related. It must have gotten switched while I was installing the LEDs back in December and I just hadn't noticed the AC wasn't working since ambient air was so cold. Very exciting to feel the AC working again!

Unfortunately I have one final step in this process - I need to fix the male pigtail barrel connector the tech broke troubleshooting the AC. I called NAPA and some other parts stores but none of them claim to have anything like the damaged connector (Compressor side). I contacted a cruiser yard and they are going to check tomorrow if they have a male pigtail I can use. I'm guessing crimping on a new male barrel connector is my best bet for getting this OEM harness in best shape. If anyone has any advice before I undertake this I would appreciate it.

Culprit Switch:

Proof the clutch is spinning again using a 14ga wire and alligator clips to reconnect the OEM harness: