AC works only after jumping AC Comp relay

Maintenance/Repairs
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1

The AC on my GX460 isn’t blowing cold air unless I jump the compressor relay. Thinking it might be the AC Senor/Pressure Switch, I tried to jump the switch through the 3-pronged connector. However, doing so I was unabile to get my clutch to engage like I can when I jump the relay, so I’m not sure if I doing it correctly.

I’ve considered replacing the pressure sensor, but recently checked and noticed my car isn’t producing heat either, so I figured it might not be the AC Pressure Sensor.

Any ideas? Thanks!

2

Check if the blend door actuator functions when switching to hot or cold air.

Tester

3

Thanks, I will check it out. If I get cold air when jumping the relay, could the blend door actuator still be the problem?

4

Have you checked the static refrigerant pressure?

Tester

5

Do you know if the compressor relay is good?

6

I added some refrigerant using AC Pro with gauge and it was in the “green” zone on the low side, so I’m thinking that the pressure is good.

7

I swapped out the horn relay to see if the problem was the relay, but it still didn’t work. Not convinced it wasn’t the relay, I purchased a new one and it didn’t fix the problem.

8

I’m curious that if I don’t have heat as well if that means it’s something other than AC related, such as the relay or pressure switch???

9

When set the temperature to 85 degrees or “HI”, there is cool air blowing from the floor vents?

10

I have the same problem with my Accord.

The the HVAC system wasn’t producing much cold air with AC on, and hardly any heat.

I checked the blend door actuator and it’s not working at all.

So the blend door must be stuck in the middle position where both hot and cold air are mixing .

And the refrigerant static pressure is at 85 PSI.

So the system is charged.

Tester

11

The HVAC operation is controlled by a driver-adjustable thermostat. The compressor relay is supposed to turn on when the passenger compartment air temp is over the thermostat set point. The first step it seems to me is to determine if the thermostat circuitry is sensing when the air temp is over the set point. If that part isn’t working correctly, you’ll never get cool air.

12

The compressor should operate anytime “Auto” is selected, hot or cold.

Go to the “Climate” screen in the center display, is the A/C button off, lit or flashing?

13

[quote=“Nevada_545, post:12, topic:184729”] compressor should operate anytime “Auto” is selected, hot or cold.
[/quote]

I wouldn’t have guessed that. Do you mean when “auto” is selected the compressor always turns on immediately, but turns off eventually if the air is too cold for the setting? Or does the compressor turn on and stay on indefinitely as long as “auto” is selected? Maybe I don’t understand what “auto” means. Maybe I don’t know what “the compressor turns on” means.

14

The compressor operates to dehumidify the air unless the vehicle operator switches it off. The compressor is shut off at 32 degrees and lower to prevent evaporator icing, like any other car.

15

Thanks for the explanation. If I understand correctly, when the compressor is turned on to “auto” only to dehumidify the air, the fans which normally blow cold air through the evaporator aren’t blowing, or are blowing at a very low speed so the passengers don’t get too cold; meanshile while the evaporator gets cold enough to condense the water in the air, which just drips out the evap drain onto the ground.

This complexity is making me feel very good about my cars’ no-A/C configuration … lol …

16

In my case, there are no error codes or blinking lights, it’s just that the clutch never engages when I turn on the air conditioning. However, if I jump the relay forcing the clutch to engage, and it blows cold air just as AC should. Since the relay checks out, maybe my question should be, what determines whether or not a relay closes to engage the clutch and give me air?

On a side note, I did mention that my heat does not seem to be working either, so maybe the malfunction with with something that controls both AC and Heat at the front end. Thanks.

17

In addition, does anyone know if a battery that is getting old might prevent the relay from closing? I did a quick check and my batter registers at just over 10v, not 12v+.

18

The failing battery should be replaced first.

The A/C button response normally to on/off commands.

If replacing the battery does not resolve the problem, check the following fuses in the instrument panel fuse block;

A/C 7.5 amp

IG 1 7.5 amp

ECU-IG 10 amp

19

I don’t think it’s a battery problem, more likely a meter problem if the battery was really at 10v, the car wouldn’t start.

20

I swapped out the battery, which didn’t help, as It_s-Me indicated… The fuses listed checked out, but I replaced them anyway, checked “all” fuses and no luck.

So, I’m still at the point that if I jump the relay, the AC compressor clutch engages. Nothing else gets it to engage. Working my way down the line, is it logical for me to think it might be the AC Pressure Sensor / Switch. (I believe the GX460 only has one near the HI pressure valve.)

Is there another relay or component that controls the relay that could be bad? Keeping in mind that I don’t seem to have heat either.

Thanks for all the suggestions. Any other ideas?