A/C not working after basic inspection

freon good, relay good (even swapped out but no luck), no A/C warning light, wiring looks good, but A/C clutch will not engage.

When i jumped the clutch relay, the clutch engaged normally.

Any ideas where to look now?

2013 access cab, 2.7 liter

Thank you

 

Got 12v to the relay coil with the AC on? If yes, bad relay. If not look upstream. Need a schematic? I know a guy...
@Jimmyh

 

The car was not on. So must be upstream?

 

@Muddinfun would know..

 

The Truck must be running to check for 12v to the relay coil.

 

Sorry need clarification.

Engine on? Or battery on?

If engine on, i did check with swapped relay with engine on and still no luck.

 

Here’s the schematic for ‘05+. Hopefully it’s the same. The last pic shows the mg/clt relay and the clutch. The AC amplifier supplies a ground for the relay coil when all the correct conditions are met. That’s all I’ve got. Get out the multimeter and start testing.

https://www.customtacos.com/tech.ol...toyewd/06toypdf/ewd/2006/tacoma/h/em01d46.pdf

 

Yep, engine on, AC on.

 

How did you check the F134a pressure?

Check the 10 Ampere AC Fuse.

Jumper across the AC Pressure Switch just to see if it will turn on normally for a short period of time.

 

^^ I'm wondering too how the OP knows the freon level is good. Did you put gauges on it?

 

I used a can of A/C pro on the low side.. the level reading was good, i added a small bit

 

AC fuse was replaced and still no luck. If I jump the AC pressure switch and it turns on, does this just mean the switch needs replacement?

 

These diagrams give me a headache, but maybe it will help you.

 

IF you jumped the MGC LT relay pin 5 and 3, and the clutch engaged, then 12v is there. Something on the LG side of the relay is not feeding to the relay. I think lol.

 

Agreed it’s difficult to follow. But it’s all there it just may take me a few hours

 

Sounds like a bad pressure switch to me.

 

After brunch and a spicy Bloody Mary I see it clearly now. lol
12v is jumped from pin 5 to 2 of the relay coil. Pin 1 on the other side of the coil goes G wire to the AC amplifier. Somewhere from there it has to go to ground to complete the relay coil circuit.
From the amplifier to ground? I have no idea.
Give me old school, power to fan switch, to thermostat, to clutch.

 

If you bypass the AC Pressure Switch and it turns on then either the switch is defective or the pressure is low or too high.

Note there are two sets of contacts one for high pressure and one for low pressure. Either condition will not allow the compressor to run. You may have put too much in when you used the suicide can of 134a.

From the print:

System Outline

The A/C amplifier receives various signals, I.E., the engine RPM from the engine control module and coolant temperature from the engine control module, etc. When the engine is started and the A/C SW (A/C control assembly) is on, a signal is input to the A/C amplifier. As a result, current flows from IG1 NO.2 fuse to TERMINAL 2 of the MG CLT relay to TERMINAL 1 to TERMINAL MGC of the A/C amplifier to GROUND, turning the MG CLT relay on, so that the magnetic clutch is on and the A/C compressor operates.

If the integration control and panel detects the following conditions, it stops the air conditioning:
∗ Evaporator outlet air temperature is too low.

∗ There is a marked difference between the compressor speed and the engine speed.

∗ The refrigerant pressure is abnormally high or abnormally low.

∗ The engine speed is too low.

∗ Rapid acceleration occurs.

 

thank you everybody. I will report back ASAP

 

Update: i bypassed the A/C pressure switch and the compressor turned on... so either bad pressure switch or The freon level is off.. the level on the low side reads normal. I even replaced the clutch relay with a brand new one (import direct 25-0279..... dealer wanted $88 for toyota replacement, auto shop said this was the correct replacement, im not 100% sure)

Best/cheapest way to test the high side before investing in new pressure switch? Assuming the high side is good, the pressure switch is the culprit.. (pressure switch looks good, no rust or corrosion, wonder why it may be bad)


Worth jumping the ac clutch and adding freon as it runs? Seems risky, especially if the freon level isnt the issue...


Thank you