Help! A/C inop after timing belt chg

Hardhatz · **Joined:** Mon Jul 21, 2014 7:58 pm **Posts:** 13

05 CRD
Over the weekend I changed belts, tensioners, CAC hoses, upgraded the fan & clutch, changed all the fluids, and stopped the EGR with a metal plug because smoke was leaking into the cabin.
During the process, I washed everything with a pressure washer.

I thought I assembled everything carefully, but I guess I'm not as bright as I had hoped.
The A/C clutch doesn't engage.
I went back and looked until I'm blue in the face, can't spot the issue..

Any sage advice from the Wisdom Gallery?

WWDiesel · **Posted:** Mon Sep 16, 2019 11:55 pm

Assuming you have a normal Freon charge on your AC system.
Does the AC/Heater blower come on and run OK? That proves you got power to the AC controls on the dash.
Check fuses No. 16 & 21 and make sure neither one of them are blown.
Check the connector to the AC clutch and make sure it is connected good and clean and dry.
Next check the connection and wiring for the LOW pressure AC switch located on top of the AC accumulator next to the firewall.
Next check the connection and wiring for the HIGH pressure AC switch mounted on a fitting located Left Front Side of Engine Compartment on the A/C discharge line near the A/C compressor.
Make sure both connections are good, clean and dry.
Either one of the above switches going bad can keep the AC clutch from engaging.
Could also be a ground problem, they are covered in the FSY wiring diagrams. There are two of them that could affect AC clutch operation.

For the 05 model
See Section 24 in the Factory Service Manual for detailed trouble shooting AC problems. It starts on page 3.
Info on the HIGH pressure switch starts on page 22
LOW pressure switch info starts on page 23.

The FSM are on line at:> http://www.colorado4wheel.com/manuals/Jeep/KJ/

Hardhatz · **Joined:** Mon Jul 21, 2014 7:58 pm **Posts:** 13

Thanks for the info and link!
So, as I'm trying to wrap my head around all this, a couple of things caught my eye...:

1. I see that the High and Low switching circuit works in series, addresses the ECU, and functions by grounding.
So, I may have overlooked that grounding point. Have any idea where that might be?

2. Concurrently, I observe that the electric fan does not come on. Before it always ran when the A/C was on.
I infer that this points to the high-pressure switch.
Mockery cheerfully accepted if I am off on a wrong tangent... :lol:

The fuses mentioned above checked out ok, and the system is otherwise AOK.

WWD, looking at your accessory list prompts me to ask other questions, but not wanting to hijack the thread, I will do it separately.

Thx!

Hardhatz · **Joined:** Mon Jul 21, 2014 7:58 pm **Posts:** 13

Uh Oh...

Looks like I'm starting a topic where I'm not supposed to...

Where should I be posting my questions?

WWDiesel · **Posted:** Wed Sep 18, 2019 12:15 am

Hardhatz wrote:

Thanks for the info and link!
So, as I'm trying to wrap my head around all this, a couple of things caught my eye...:
1. I see that the High and Low switching circuit works in series, addresses the ECU, and functions by grounding.
So, I may have overlooked that grounding point. Have any idea where that might be?
2. Concurrently, I observe that the electric fan does not come on. Before it always ran when the A/C was on.
I infer that this points to the high-pressure switch.
Mockery cheerfully accepted if I am off on a wrong tangent... :lol:

The fuses mentioned above checked out ok, and the system is otherwise AOK.
WWD, looking at your accessory list prompts me to ask other questions, but not wanting to hijack the thread, I will do it separately.
Thx!

Yes, the high and low pressure switches are wired in series according to the FSM.
As to grounds, the FSM actually shows you pictures of where all the grounds are located.
According to the FSM, one (G103) is on the side of engine right near the oil dip stick tube bracket above the starter.

Grounds G103, and G113.
See these pages in the FSM
G103 (Diesel) Right Front Side of Engine, diagram 21 -- See Section 8W-91 page 35
G112 Left Front Side of Engine Compartment, diagram 31 See Section 8W - 91 - page 44
This one is right below the power distribution center, it is right behind the left front headlight assembly located on top of the fender well.
Quite a few have had problems with this ground.

Hardhatz · **Joined:** Mon Jul 21, 2014 7:58 pm **Posts:** 13

Fuses good
Tried bypassing at low pressure switch, no go.
I didn't try shorting past the high pressure switch, as it has 3 wires and Im afraid I might mess up.
I couldn't see a procedure for that...

There is a 0-G main ground wire near the dipstick where it goes into the block. Is that G103?

WWDiesel · **Posted:** Thu Sep 19, 2019 1:40 am

Hardhatz wrote:

Fuses good
Tried bypassing at low pressure switch, no go.
I didn't try shorting past the high pressure switch, as it has 3 wires and Im afraid I might mess up.
I couldn't see a procedure for that...

There is a 0-G main ground wire near the dipstick where it goes into the block. Is that G103?

I would not try that on the High pressure switch, even though it is called a "switch" it actually is a pressure transducer. That is why it has three wires.

Yes, the ground by the dipstick is the G103. But be sure and check the others I listed.

Help! A/C inop after timing belt chg

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