I just purchased a 2005 (Built 4/04) Scion XB. The a/c doesn't blow cold. The light comes on on the dash when pressed. I appear to have power at the plug on the compressor (my multimeter died today, hence appears. Using the old test light) but the clutch doesn't engage. On the car side of the compressor plug there are two wires, one black with a white stripe and one blue with a black stripe. According to my wiring diagram, the blk/wht goes directly to 12v hot via a/c 2 fuse 7.5 amp. The fuse it good. The power is good. The blu/blk wire goes to the engine control module (ECM). I presume the wire going to the ecm is a switched ground wire? On the compressor side of the plug, there are 2 wires. One is black, one is red. I have grounded one side and 12v the opposite, I have done the same reversed, and I have applied 12v to both prongs and the clutch magnet still doesn't engage. Here are my questions....
1. Does the ECM in fact use a ground to switch on the compressor?
2. Are my original test procedure correct, ground one side of the compressor plug and 12v the other prong?
3. Do they sell just a clutch for the compressor, or do I have to replace the complete compressor?
4. Is this a common part to fail on these?
Maybe low pressure/refrigerant in the system which would prevent the compressor from turning on.
__________________
"Fools", said I, "You do not know, silence like a cancer grows.
Hear my words that I might teach you. Take my arms that I might reach you"
But my words, like silent raindrops fell, and echoed, in the wells of silence.....
Jason Johnston
Toyota/Scion of Des Moines
(800)342-7045
The pressure is actually too high right now but that is irrelevant. While you are correct that the compressor wouldn't kick on by itself in those condition, the clutch magnet should turn on when I apply straight power to it. My question isn't about the a/c system, it about the magnetic clutch on the compressor.
Ok after looking at an xB.....i don't see a clutch. I was thinking that the xB has a variable compressor. It should always be spinning.
So, pressure in the system has everything to do with the situation since it is a variable compressor, a high pressure situation in the system would render the A/C system to appear inactive until the pressure was returned to normal.
Hopefully putting a full 12V to the compressor didn't burn it.
Send me yor e-mail address and I'll send you some info on how to properly diagnose the compressor.
and to answer your first questions...
Quote:
1. Does the ECM in fact use a ground to switch on the compressor?
The ECM uses many sensors to determine the needed work load of the a/c compressor and adjusts the output as such. Everything in the car relys on ground. Without reading the electrical wiring diagram however, I'm not sure
Quote:
2. Are my original test procedure correct, ground one side of the compressor plug and 12v the other prong?
Being a varable compressor, i would [u]think[/] that the amount will vary based on the ecu's determination of needed load.
Quote:
3. Do they sell just a clutch for the compressor, or do I have to replace the complete compressor?
Whole unit/compressor
Quote:
4. Is this a common part to fail on these
Not really. I've never replaced one in the 10 years I've been with Toyota
__________________
"Fools", said I, "You do not know, silence like a cancer grows.
Hear my words that I might teach you. Take my arms that I might reach you"
But my words, like silent raindrops fell, and echoed, in the wells of silence.....
Jason Johnston
Toyota/Scion of Des Moines
(800)342-7045
I believe my compressor is bad. I am bypassing any pressure switch and going straight to the compressor. There a 2 wires. A red and a black. One has constant power, the other goes to the ecm. The one going to the ecm should be a switched ground and would turn the compressor on. This is what I am thinking the system is. But am I correct? I am just trying to test the compressor.
Or is the compressor grounded through the body of the unit and of the two wires, one goes to the 12v (I know this for sure) and the other goes to ecm. Could the one going to the ecm actually be another 12v for a built in relay?
I connected my genisys scanner and there is no a/c controls via the the ecm. And no bcm or any other kind of computer to control the a/c system.
hold on and I'll send you the checks........Don't short your compressor.
__________________
"Fools", said I, "You do not know, silence like a cancer grows.
Hear my words that I might teach you. Take my arms that I might reach you"
But my words, like silent raindrops fell, and echoed, in the wells of silence.....
Jason Johnston
Toyota/Scion of Des Moines
(800)342-7045
__________________
"Fools", said I, "You do not know, silence like a cancer grows.
Hear my words that I might teach you. Take my arms that I might reach you"
But my words, like silent raindrops fell, and echoed, in the wells of silence.....
Jason Johnston
Toyota/Scion of Des Moines
(800)342-7045
It is a magnetic clutch. On plug, terminal 1 is ground and 2 is 12v. So the the clutch magnetic is bad. Time for a new compressor. Car isn't here right now to confirm colors, but I presume red is 12v and black is ground. See (3).
My experience with my wife's 2005 Scion Xb is that failing to energize the magnetic clutch is a chronic problem. I've had two instances of it quitting and in both it magically began to work again following access by the dealer.
The first was about six months ago and then about two days ago. I checked the refrigerant (>100 psi, compressor wasn't working), the suction pressure cycling/radiator fan switch (okay) and the fuses AC1 and AC2 (okay). Depending on the documentation you can get, it shows the ECU supplies ground to the compressor which has battery through the AC2 fuse to the compressor. The documentation isn't too reliable, however (I saw three versions of the 2005 Xb pressure switch posted). Some sources show a tach pickup on the compressor; some don't. The tach is used to determine if the compressor is not slipping or seized after startup. If it fails this test, the ECU will refuse to engage the compressor and apparently sets a proprietary diagnostic code and locks the compressor out. This will also happen if water (such as a car wash) gets on the belt slips.
I had the dealer access the diagnostics and clear the codes and the a/c worked fine. This is the second time it has happened. The first, they found nothing wrong. The last, they concluded it was the clutch and required a compressor ($1500 parts and labor), but it magically worked after the diagnostic test clearing - but not before.
I have no codes, even access it with a tech 2 scanner and still nothing. After my original test of the compressor, I figured the clutch was bad. I was just trying to figure out if my test procedure was correct to figure out if my diagnosis was correct. I am a car dealer, so $ is the most important factor. I went on car-parts.com and ordered a used compressor shipped to the house for $115. The dealer wanted $875 my cost on a new one. I should get that soon and hope gets her going.
So have we concluded then that the clutch is Internal since there is no external clutch?
__________________
"Fools", said I, "You do not know, silence like a cancer grows.
Hear my words that I might teach you. Take my arms that I might reach you"
But my words, like silent raindrops fell, and echoed, in the wells of silence.....
Jason Johnston
Toyota/Scion of Des Moines
(800)342-7045
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