Honda Pilot - Honda Pilot Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter #1
I have a '04 Pilot with 172K miles and have been having A/C problems since about a year ago: there was one day A/C was not cool enough and I added a can of R134A which made A/C cool for one season, and then one day it stopped cooling altogether.

Suspecting that there was a leak somewhere, I bought a can of AC trace dye and added to the AC line. No visual leak could be identified with the U/V flashlight in accessible areas. In April, 2019 I replaced the condenser after spotting damaged/dented metal fins, though without signs of leak. Before adding R134a, I vacuumed the system, but I could only get a 27mmHg vacuum, not a 30mmHg one. The ambient temperature was mid 50s then and I stopped pursuing it.

In the past week (Aug., 2019), I tried it again and could still get a vacuum of 27.5mmHg. I then tried to add R134a but the system only sucked in 1x 12oz can, while the system needs 24.6oz - 26oz of R134a.

I suspect that there is a leak somewhere, but felt frustrated that I couldn't locate it with the A/C dye. I am also puzzled by why the system could only suck in ~12oz R134a -- I had hoped that a 27.7mmHg vacuum is good enough to take enough freon. When measured with the manifold gauge, the low side pressure is about 25-30 psi and high side ~55psi when the ambient temperature was ~75-80F, both felt low IMO. The A/C currently blows mild air and it's getting worse since the day when new freon was added.

Any suggestions from piloteers before I take the car to an indy A/C shop? I had many past bad experience with the local dealerships and don't want to deal with them again.

P.S. All relays, compressor, radiator and condenser fans are working OK.
 

·
Registered
Joined
·
135 Posts
"and high side ~55psi when the ambient..."

Seems like the high side should run higher than that. Something is restricting. maybe plugged expansion valve.

My 04 pilot service manual says for the pressure switch (on the high side pressure side after the condenser)...when refrigerant is below 28 psi and above 455 psi it closes or open the circuit for the ac clutch operation. So i suspect the 455 psi is an over-pressure protection point and the clutch operate between 28 psi and something high.

Is your ac clutch cycling on stays on all the time?
 

·
Registered
Joined
·
135 Posts
I meant to say possible restriction between the switch and compressor, or a broken expansion valve that won't allow the pump up in pressure. Just an idea. The low side seems to be in range, so it could be the expansion valve.
 

·
Registered
Joined
·
830 Posts
I'm not an AC tech, but if you cannot hold a 30 mm Hg vacuum, doesn't that mean you still have a leak?

Oops, sorry, I see that you already mentioned this is your post. Then it would seem that finding the leak is your next step. Have you tried a freon sniffer? IDK if its possible to rent this tool, but a sniffer should be more sensitive than the UV dye test.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #5
Thanks @delta_p and @STMech .

I hooked the gauge yesterday and measured the pressure again: when car was off, the equalized pressure was at about 70psi. When the engine ran, low side was 15psi and high side was 65psi.

Since I had a can that had been pierced, I managed to add it to the system and brought the low side pressure to 30psi while high side to 100psi when the ambient temperature was low 70s. The compressor seemed stayed on all the time when recharging since I turned the ac knob to the lowest setting. @delta_p : is it a problem that the compressor stayed on?

In retrospect, the first time when it was recharged, I might have kept the red manifold valve (high) open when recharging freon. So when the high side pressure reaches the level of the can, it stopped the freon from getting into the system.

The ac blows cool (though not very cold) air now. Last time it did the same and lasted for about a week. I am almost sure that there is a leak somewhere and I will try the freon detector next, as @delta_p suggested.
 

·
Registered
Joined
·
1,649 Posts
Buy a UV light from the ebay and a can of Duracool with dye. With that you would at least see where it is leaking. I bet it is leaking from the suction Y-pipe under the hood or under the bottom of the car.
 
  • Like
Reactions: ccbcc

·
Registered
Joined
·
135 Posts
It's ok that the compressor continue to run. The expansion valve has a thermal regulator that will move based on the goes in and goes out temperature of the evaporator. It is setting a restiction to produce the cooling of the freon. and you ran the ac on full. Usually a short cycling of the compressor would be when there isn't enough freon.
 

·
Registered
Joined
·
135 Posts
When you turn off the car and have the gauges hooked up you can watch the low pressure and high pressure come to the same pressure. if it takes an extremely long time like more than 15-20 mins, this would be indication of a restriction somewhere between the gauge hook ups.
 

·
Registered
Joined
·
31 Posts
Discussion Starter #9
When you turn off the car and have the gauges hooked up you can watch the low pressure and high pressure come to the same pressure. if it takes an extremely long time like more than 15-20 mins, this would be indication of a restriction somewhere between the gauge hook ups.
Thanks for the great tip!
 

·
Registered
Joined
·
2 Posts
On our 2004 Honda Pilot I bought the seal kit, replaced the expansion valve, seals, and schrader valves. Leak was solved but hot air through the vents... and cold air through the rear vents when turned on. Need to replace the valve under the hood next to the fire wall next. Don't forget the cabin filter, ours was pretty rough thanks to a mouse.
 
1 - 10 of 10 Posts
Top