A/C light blinking

You didn't say that the AC was not on in your first post...

You do know that the AC is on when in Defrost Mode right?

 

The compressor is also on when the bilevel (foot/defrost) mode is selected. There is a mod to keep the compressor off when the defrost and bilevel modes are selected. In some dry cold areas having the compressor on works against you in the defrost mode.

 

Thanks, I didn't realize the a/c compressor was on in defrost mode. I thought I had to manually turn the a/c on if i wanted it to help in defrost mode. Whenever I drive my truck the fan is on low, and usually in defrost mode or bilevel. Could that be using the compressor too much and cause it to fail? Also, I haven't driven my truck as a daily driver for the past 3 years, it's been mostly sitting or getting weekend use. 67,xxx km on an 08' that was bought it 07'. I recently changed jobs and am now driving it daily.

 

^^Yep. The more you use it, the faster it wears out.

We are getting a bit off the topic here as you have another question on the table. Hopefully someone in the know can assist you.

 

I thought OP's question was answered. Also, does anyone know the part numbers for the compressor, I might as well start looking at prices for a new one as I'm pretty sure thats what's wrong here.

 

Slesse, I will look at the factory manual for ya tomorrow to see the known causes of the blinking A/C light.

Go to RockAuto.com and do the drill down for your truck. You will see the Delphi and Denso compressors. Both are the OEM compressor. Even though they have different names and different part numbers they are identical. So get the cheaper, which will likely be the Delphi.

This is currently the cheapest source of the compressor. But don't buy yet until you check out those things I will give you tomorrow.

Also, know that RockAuto has its famous 5% off code listed here on the forums. Do a search and enter it at checkout.

 

Slesse, curiously I could not find anything in the manual about the flashing A/C light. However, the following will likely cause it:

1. Magnetic clutch relay per Post #'s 2, 3 above.

2. Electrical connections on compressor. Make sure they are connected and there is not a loose ground on the compressor. Make sure the Philips screw there and tight.

3. Does the compressor shaft move? Loosen the drive belt and try to move the end of the compressor (not the drive pulley) with your hand. Seized or nearly so?

4. Magnetic clutch. Note: the manual discusses testing and replacing certain parts on the compressor. However the magnetic clutch costs about $450 and the magnetic pick up sensor costs about $80.

INSPECT MAGNET CLUTCH ASSEMBLY
(a) Inspect the magnet clutch assembly.
(b) Confirm that the magnet clutch hub and magnet
clutch rotor lock when the battery positive lead is
connected to terminal 1 (MG+) of the magnet clutch,
and the negative lead is connected to the earth wire.
If the operation is not as specified, replace the
magnet clutch assembly.

5. Compressor magnetic pick up signal sensor.

INSPECT COMPRESSOR PICK UP SENSOR
(a) Check the compressor pick up sensor voltage.
(b) Connect the positive (+) lead from the battery
to terminal 3 (SSR-) and the negative (-) lead to
terminal 1 (MG+), and measure the voltage
between terminals 1 (MG+) and 2 (SSR+).
Standard:
2.0 to 3.0 V
(c) When surface A of the compressor pick up
sensor is close to the S-pole, the voltage
between terminals 1 (MG+) and 2 (SSR+)
increases. When it is close to the N-pole, the
voltage between the terminals decreases.
If the result is not as specified, replace the
compressor pick up sensor.

6. System low on charge. Inspect pressure switch on high supply line located on RH side of truck. Follow aluminum outlet pipe from condenser toward firewall. It is located adjacent to the RH headlight.

INSPECT PRESSURE SWITCH
(a) Disconnect the pressure switch connector.
(b) Connect terminals 1 and 2 of the pressure
switch connector on the vehicle wire harness
side using a service wire.
(c) Start the engine.
(d) Turn the air conditioning switch on and check
that the magnet clutch is turned on.
(d) Check that the magnet clutch is turned off when
disconnecting terminals 1 and 2 (that are
connected in the prior step).
Standard:
Terminals 1 and 2 connected: Magnet
clutch is ON
Terminals 1 and 2 disconnected: Magnet
clutch is OFF
Replace the pressure switch if the magnet
clutch operates normally.
Inspect and repair the wire harness between
the pressure switch and the ECM.

7. A/C Amplifier. You have to remove the glove box to get to it. It is located on the large round cross bar above the glove box opening and a single 10mm hex nut fastens it to a plate on the bar. The nut is on the top and you have to feel for it. No test procedure is given.

 

Thanks Taco'09!!! I just did the a/c defrost mod this morning (after i noticed the problem) it's a fix in the short term as now my engine does not drop in idle after fist start up. But the problem is still there when I press the A/C button. I'm starting with the cheap and easy one first. I'm picking up a new relay on saturday and will try that first. +rep for the awesome and thorough diagnostic!!!

 

Slesse, no problem. Sounds like you are making good progress on your own. If you happen get to the point of doing the compressor, hopefully you will not, give a shout as I have done a compressor.

Best of luck.

 

What the......... Just checked prices on compressors at RockAuto. They have had $60+ price increase from what I paid 4 months ago. Looks like the $323 at Amazon for a Delphi, the OE compressor, is actually the current best deal for an OE compressor:

$523 Delphi A/C Compressor - CS20055

http://www.amazon.com/Delphi-CS2005...rId=001&n=15684181&s=automotive&vehicleType=6

 

I had this happen to me today on my ride home. My ac has never been real cold from day one. I had it charged last week and this was the first time I used it. The original charge was lower than the under hood sticker. When I was in traffic I could feel the ac temp changing from cold to warm as the compressor cycled. Then it was just hot air, I looked down and the light was flashing. I turned it off and on and it was good for less than a minute and started flashing again. I left it off for about a half hour until I was out of traffic. It worked flawlessly for the rest of my hour and a half commute. My thought is that in the heat the pressure built to a point that it shut down on the high pressure switch. Any opinions?

 

BostonBilly, I'm real curious about how much they charged your system. You said that "the original charge was lower than the under hood sticker."

How did they know this? 2nd Gen. Tacos act about the same goofy way when either slightly overcharged or slightly undercharged. The only way to properly charge the system is to evacuate the system, pull a deep vacuum, and then charge precisely by weight according to the label under hood. Note: you can not do this by using the little cans as there is refrigerant loss in both the hoses and the cans.

Also, did they thoroughly check for leaks?

If you have some manifold gauge readings we can try and diagnose any possible problems but there appear to be more problems with improper charging than most everything else. Next in line are compressors dying and there are plenty of those.

 

Ya they used the machine. They machine recovered 1.1 pounds and the tag calls for 1.4 or something. They installed the tag amount after pulling a vac for the allotted 15 minutes. The compressor was short cycling and the low side was dropping down to a little less than 20 on the gauge he added a little more till he was up to 30 on the low side and the compressor wasn't cycling on and off quickly. I agree with your thought that he put to much charge in. I will monitor how it works and bring it back if it continues

 

BostonBilly, try this. With the A/C running for awhile, observe and feel the low pressure return line back to the compressor a couple of inches from the firewall. It is the larger diameter of the two lines.

If it is frosting up there is too much refrigerant in the system. The reason being it has run out of room to expand in the evaporator, is still in liquid form, and seeks to convert the remaining liquid to gas in the return line back to the compressor. Too much liquid can slug the compressor and destroy it.

The return line there should feel slightly cold and even form some condensation but not frost up.

 

Thanks will do

 

The A/C system in our trucks is simple. It will not work if pressure of freon is below 20psi on low side with compressor ON. it will also not work if pressure goes over 50 PSI on low side with compressor ON.
So the sweet spot is probably around 40 PSI +- on low side with truck at full temperature when its 100F + outside.
Connect gauge to low side and check the pressure. It will tell you right there if you have problem. Its very easy to overcharge the system. So when truck heats up A/C will stop working.

 

Which is what I think happened. The low side was at 20 or lower when clutch was engaged. It was topped off to 30 with clutch engaged. I was in heavy traffic moving slow so less air flow over condensor cause heat saturation and a pressure rise.

 

This is timely. My A/C stopped working a few days ago (after having it at the dealer for the 25k service). The A/C light wasn't flashing and there wasn't any other indicator of a problem--just no cold air coming out. It didn't seem like the compressor was engaging. I pulled over hoping maybe it was a fuse. Opened the fuse box in the engine bay, examined a couple of fuses and what might've been a relay and didn't see any problems. Then I started it up again and everything was fine. I'm wondering if maybe I shook loose a stuck relay when I was poking around.

Also, how do you test the pressure in the system? Is a special guage required?

 

May be low on 134a gas. I believe if the computer detects any issues and keeps the system off. May or may not blink a light.
If it's low on gas, it will fast cycle and the computer may sense this and shut it off.
So when you stopped, and shut it off, the heat radiating from the engine increased the pressure in the system enough to start it working again.
Yes, you can buy a low side guage from Wally and watch the cycling. On at about 40-45psi, off at about 30. The question is what do you do then?
A full guage set will look at both sides if you want to pay for it.
On my 2000 sienna, with rear air, it was simple to add a can of 134, watching the pressure so as not to over fill. Seat of the pants; but maybe not a good idea on 2nd gen tacos

 

I just wrote that for somebody else but hopefully it helps.

All one has to remember to charge their A/C when car has been driven while its hot outside. Than do it slowly.