AC clutch not engaging

In the print below the Light Green Wire is from the IG1 No2 Fuse.

There should be 12 VDC at coil winding terminal # 2 whenever the truck is on.
When you turn on the AC do you get a ground at the relay terminal # 1? This ground is supplied by the AC Amplifier. under the dash.



The AC Amplifier is up above and to the Right of the Engine Control Module.

 

I checked the pressure switch continuity. this is how I checked it, in case I did it wrong;
- car keys out of the ignition
- set the multimeter dial on ohm -20M
- placed the probes on the switch contacts ( not the wires side)
- reading was 1
- did it again with the key in the ignition and the ON position (truck not started)
- placed the probes on the switch contacts
- reading was 0 (zero).

 

I know the switch has a problem. sometimes it works on high only. but it is a intermittent problem that comes and goes. in any case, I order the kit to replace blower resistor.

 

The above indicates your sensor is good. FWIW truck on/off etc makes no difference for the sensor check.

Looks like Jimmy can take you down the next level of the rabbit hole!

 

Check for a ground connection when the AC is turned on at the relay coil terminal # 1 as per the schematic I posted above.

If you are not getting a ground when you turn on the AC then you are missing one of the qualifiers listed above or you have a faulty AC Amplifier or a wiring problem.

 

Hi Jimmy

Somehow, for the past day and half AC is working without slamming the hood or any relay jump.

pardon my ignorance, how do I test the ground connection for the relay coil terminal?

thank you

 

Pull the relay from the socket.
Set the Multimeter to check resistance.
Connect one meter lead to terminal # 1 of the relay socket.
Connect the other lead to a good body ground or the negative battery terminal.

With the AC off the meter should read open ( OL ) or a at least a reading in the millions of ohms.
With the AC turned on it should read zero ohms or very near zero.

 

Hi Jimmy

the readings I got are the same; set the mutlimeter 200m
AC off - 0 .9
AC on - 0.9

thanks

 

That is reading terminal # 1 of the relay socket to body ground of the vehicle, taken with the engine running and the relay pulled? You should use a smaller range setting on your meter.

If both on and off are the same, that isn't right.

 

I tested again with smaller setting-20m

engine off - 0(zero)
engine on & AC on = 0.26 ( compressor clutch stopped when relay was removed).

 

I am confused.
Are you sure you are reading resistance between terminal 1 and body ground?

Truck on and A/C off it should read open resistance (OL) between terminal 1 and body ground.
Truck on and A/C on it should read a short between terminal 1 and body ground.

Do you have 12 VDC at Terminals 2 and 5?
You should when the truck is on regardless of the A/C being on or off.

 

may be I'm mixing up the terminals. are these the correct terminals (image)? the one I labelled terminal 1(socket), is the one I'm getting the readings from.

thanks

 

I am talking about reading the relay socket terminals. What you are looking at are the relay terminals.

Pull the relay out completely. You should see this and as you can see your labels are wrong on the relay image above.

 

set the multimeter at few different settings 20m,2m,200k,20k,2k. with engine on, ac on . or engine on ,ac off.
not getting any readings from 1 nor 2 terminal sockets - just 1(one).


am i missing something?

 

I have gotten wrapped up in the ground connection. I see you never said if you are getting 12 Volts at terminals # 2 and # 5.

Are you getting voltage at those terminals with the truck on. If the answer if no you have a fuse or wiring issue between the fuse and the relay socket.

I cannot say if you are missing something or not, but if the readings are all the same on terminal # 1 on or off it seems you have an issue with the wiring to the A/C Amplifier or the A/C Amplifier itself.

I wish I were there to actually put hands on this. It's hard not being able to see this in person.

 

When you select AC on the dash do you get 13 volts at the mag clutch wire? If yes then the clutch should be engaged and the compressor pumping. If not push on the clutch with a hammer handle and see if it engages. It might just have too big a gap for the magnet to pull it in. That's why it would work when you slammed the hood sometimes

There are little shims that can be removed to help with clutch clearance

 

Hi Jimmy

with the truck on, tested voltage;
-multimeter @ 20V
-terminal 2 & 5 readings were; 13.67

would the amplifier wiring be causing AC dial problems too?or that is not related and it is blower resistor problem?

I know, it is hard to do diagnostic online. may be we could do it over Zoom

thank you, I appreciate all your expertise and help.


Oh, this may be related or not!
for a while , I had the check engine light and traction light on. OBD2 results were P0418 and P2441. After I started sticking wires into the relay socket and pressure switch(AC problem troubleshooting), the lights went away. hmmmm

 

The fan selector switch is probably a separate issue. You can easily verify that problem by looking at the connector under the glove box. It’s obvious because of the scorching on one terminal. It should still operate on high though.

 

1) - This is good voltage is good and making it up to the Clutch Relay and rules out 1/2 the circuit.


2) - What are you calling the "AC Dial"?
The Damper Servo Motor (Air Mix) is controlled by the Dial in the control unit.
The Damper Servo Motor (Air Inlet) and the Damper Servo Motor (Air Vent Mode) are controlled by the AC Amplifier.
The blower resistor has nothing to do with the AC Clutch.



3) - Sorry, I'm an old fart and try to stay away from Zoom as much as possible.



4) - P2441 and P0418 have to do with the secondary air injection system and I see you have a 2010 so this must be a 2TRFE 4 Cylinder engine correct? The 2010 V6 did not have a secondary air injection system.

P2441 is no exhaust pulse detected when the injection valve is commanded open.
P0418 is for for "Secondary Air Injection System Relay A circuit Malfunction".

Your injection valve is probably sticking a bit.

Now since we know we have voltage at the relay terminals # 2 and 5 we need to find out is the relay is actually closing.

See the Violet ( purple ) wire attached to terminal # 3 of the relay socket. We need to turn on the AC and check that wire for voltage down on the AC Compressor Clutch Connector if you can get to it. It should read the same as above at the relay 13.67 volts.

If it doesn't then the relay is not closing or there is a problem with the purple wire. This is either due to a defective relay, the AC Amplifier isn't connecting a ground or the wire is broken

 

Hi Jimmy

sorry for the late reply- had some health issues to deal with.

-Finally, installed the Blower resistor. the ac fan dial is working fine now, but the same problem exist( clutch not kicking in). I guess that wasn't the cause.
- the purple wire you referring to is it this one? pictures below.

-I tested for voltage - I'm getting 0.3V.