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Discussion Starter · #1 ·
VEHICLE: 05 Pilot w/ 148k miles

BACKGROUND: Up until about a month ago, a/c worked flawlessly. A month ago I was sitting/idling in the veterinarian parking lot for 3 hours (due to COVID and contactless drop off/wait) and the air stopped being cold and went warm. Turn off vehicle, start again in 20 minutes and it gets cool again, but hasn't been cold since. To date, it does cool, but know it's not functioning 100% and as cold as should be.

ISSUE: Condenser fan doesn't come on when a/c is turned on - only cooling fan.

TROUBLESHOOTING:
1. Bought recharge kit and used the gauge on it prior to adding anything and gauge read "yellow" no additional freon needed. ~50psi
2. Switched out condenser and cooling fan relays and same outcome.
3. All fuses (under hood and driver side inside) check out.
4. Fan control relay (under washer fluid neck) causes the same issue with it removed or in place.
5. Compressor clutch kicks on when ac starts and does not cycle.
6. Tested both ECT sensor connectors by "jumping" them and same result.
7. Condenser fan tested and works with cooling fan connector plugged into it.

CURRENTLY: I can get both fans to turn on in low mode when ac is turned on and the cooling fan relay removed. As soon as I put cooling fan relay back in, ac fan stops and cooling goes on high.

I've spent hours on the forum and internet, any thoughts?
 

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It could very well be your A/C condenser fan motor (passenger's side, dependent on A/C turned on) has given up. Check the fan motor and see if it has a high temperature (don't burn yourself!) from being energized without being able to turn. You could also check the DC power to the fan, to see if it is getting electricity when the A/C is switched on.

I am not a technician and recently had cooling issues with my 2003. Like you, I bought a recharge kit and tried adding some coolant, but no improvement. When I took my Pilot to a mechanic, he checked the cooling system in addition to the A/C and found 1) broken radiator cap, 2) intermittent engine cooling fan (driver's side and dependent on engine temp), 3) Hi and Low pressure ports for A/C were off. We replaced the radiator cap and added some coolant ( coolant was beginning to blow out of the reservoir and bad cap prevented coolant returning), tapped on the fan motor to get it going. As soon as these adjustments were made, my A/C began performing great. He also evacuated the freon, ran a vacuum on the A/C system to remove moisture (about 20 minute process) and replaced freon to the proper pressures (Low and High).

We did fine until we got out to a remote area a week later (West Texas in July) when the engine fan finally crapped out and the radiator began to boil over every 75 miles. We limped home and replaced the fan assembly (good luck finding just the motor), but by then the radiator had been blown. I am now looking to replace it, along with other cooling system parts (hoses, thermostat, etc).

All that to say: your A/C is dependent on your engine cooling properly and a BALANCE of pressure between the Low and High pressure freon lines, so keep a sharp eye on both. Also, the cheap gauges they put on those freon refill cans are pretty useless and led me into a 'false sense of competence'. You may indeed have an electrical issue involving relays, fuses and temp switches, but don't loose sight of the big picture, which is fairly complex and interdependent.

Good Luck
 

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Discussion Starter · #3 ·
Thanks for the detailed reply. I know the a/c fan motor (passenger side) definitely works; when connected to radiator fan plug (to test) it runs and also when I have the cooling fan relay removed they both function as they should (minus no high speed).

I'm perplexed so have just been running w/o the cooling fan relay during these hot months. No issues whatsoever with overheating.
 

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This appears to the major problem: 5. Compressor clutch kicks on when ac starts and does not cycle.

You could also try replacing the AC clutch relay for about $12. You said the clutch kicks on but doesn't cycle (edit - had the wrong word) - this is most likely due to low refrigerant. When you kick the system to Lo = max AC = there's not enough refrigerant to keep the system running.

To me, even though you tried to recharge it - the problem sounds like low refrigerant or a bad (dying) compressor. When refrigerant gets too low the AC clutch won't engage properly or keeps endlessly spinning, which effectively causes problems to the system. When the refrigerant gets low enough the compressor won't even kick on, this prevents the clutches from overheating and destroying other components. And if the compressor and/or clutches died, you obviously won't get any air...

The quick and easy 'test' and potential fix is to rent a set of actual manifold gauges (OReilly, Autozone, etc.) or buy a set of gauges off Amazon, then measure the pressures in both lines. Grab a few cans of 134 when you get the gauges and prepare to recharge it. It's also possible that you need to evacuate and reprime the entire system - you may have moisture in there that needs to be removed before adding new refrigerant.

Here's also a simple chart that lists simple problems associated with lo and high pressures. The simple recharge kits only look at the low pressure line:


However - I'm not sure I completely understand this statement - "As soon as I put cooling fan relay back in, ac fan stops and cooling goes on high."

Are you saying that when you put the relay in the AC immediately goes to LO setting and you get maximum air flow? I'm having trouble understanding what you mean with the word 'high'...
 

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You may want to review this post regarding the fan speeds for the coolant temps. It discusses operating temps for the fan motors and has some schematics:

 
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