2004 3.5L AC trouble sensor suspected.

[Fool_4]

I have just changed my compressor, dryer accumulator, condenser coil, TXV and flushed every hose and the evap coil really well. Firing the engine up after drawing the system down and checking for any leaks of course, the compressor will not engage. I checked the compressor fuse and it's good. There are two sensors I have seen in the system, one on the compressor in series with the clutch and one more that is in the manifold block where the hoses connect to the compressor, What is this sensor? Anyone know?

[fdryer]

The sensor on the compressor is a thermal protection device to detect excessive high temperatures above 400F to shut down compressor operation and the evaporator low ambient temperature sensor is used to detect and shut down the compressor if temps drop below 37F at the sensor.

At the risk of seeming ignorant, was this system filled with the correct amount of R134a and Pag oil?

[Fool_4]

I got as much r134a into it as it would allow without the compressor running. About 14oz I would guess of a required 28 I think whatever 1.75lbs equals.
About the overtemp switch, I have since jumped the compressor relay and it comes on just fine so the opvertemp switch must be made.
The side effect of my bypass was an overheat of the condenser coil, seems the two engine fans are not brought on until the AC decides the compressor should be running.
I am leaning more and more to the temperature sensor in the hose manifold on the compressor.
Any testing thoughts? Diagram would be like a godsend.
What is the sensor a thermistor/RTD I am guessing as it requires 5V and sends back some current, must be another resistor in the ECM the signal forms a divider with to give some voltage level to the ECM's input. Any idea of a good place to intercept this wire?
Am I making sense?

[Fool_4]

The PAG oils is a little low, the compressor came with a tag claiming 120ml was injected at the factory. I was planning on picking up one of the r134a oil charge cans (4oz) and getting 3/4 of it in to bring the PAG charge to 7oz as spec called for.

[Fool_4]

And BTW THANK YOU fdryer, I saw a post of the dropping the frame member to get clearance so you could change the compressor!
The first time I changed this puppy, I didn't see that helpful little hint, needless to say I went around telling everyone about my experience and what all was involved in changing the compressor on the 3.5l 04 Vue. My description was something like, start taking off parts, keep taking off parts until there is an old compressor sitting in your driveway. Walk over to the old compressor with new compressor in hand and swap the two. Start putting parts back, keep putting parts back until you see a Saturn Vue in your driveway.

I am not exaggerating. That 1st time was a BEAR! I learned a valuable lesson though, Flush, Flush then Flush some more, Oh and did I mention flush again just for fun.

[Fool_4]

Sorry to post all these fragments, but there was one other piece of data I need to mention. The service vehicle soon light just came on during the test run. This is the 1st time I have had this light come on, as normally it's the service engine soon that I have problems with (gross evap leak, but that's another story). My bluetooth scanner and phone running "torque" shows no DTC, so this must be some DTC that's encoded differently, maybe HVAC related????

[fdryer]

While three posts are scattering your thoughts, I can manage them.

1-Was the entire amount (1.75lbs) of R134a injected or not? If you aren't aware, once half a pound or more of R134a is injected with the compressor off, turning on the compressor and running the engine up to 2k rpm will draw in the rest of the R134a. Idle rpm doesn't work for measuring pressures or filling the system to completion.

2-Pag oil must be added to a flushed system. Procedures require a rebuilt system to use the amount required to be distributed to all the major parts, compressor, condenser and evaporator coils. This allows the compressor the best chance of lubrication when first turned on.

3-If you need service manual info, pm me an e-mail address so I can attach files.

4-The error may be a/c related but only if its sensor related that isn't cooperating.

[Fool_4]

Here lies the rub. My compressor will not run, unless I just out the compressor relay, and while this is going on the cooling fans are not running so the condenser coil starts to overheat really fast.
No I only was able to get 14oz in or so.

[tiger862]

With a complete empty system you need to carry it to shop to get filled correctly or you will lose. You are supposed to fill through high side with correct machine and engine off. I have seen some get lucky and bypass circuit and get compressor on and fill through low side but premature damage was done. Good luck.

Oh you can try to put defrost on and see if compressor comes on then maybe you can fill it that away. I have not tried it this way but defrost normal signals compressor to come on. Be careful with jumps cause you don't want to fry BCM.

[far2grumpy]

Originally Posted by Fool_4

Here lies the rub. My compressor will not run, unless I just out the compressor relay, and while this is going on the cooling fans are not running so the condenser coil starts to overheat really fast.
No I only was able to get 14oz in or so.

I'm not sure if you PM'ed fdryer for data so I'll attach two thumbnails - one with AC interlock wiring and the other is cooling fan wiring.

The cooling fans run at two speeds ...

a. If PCM wants low speed only - Cool Fan Relay 1 is latched and both fans run in series using 6 volts each.

b. If PCM wants high speed - all three relays are latched and each fan runs from 12 volt B+.

c. You could run both fans low-speed by removing Cool Fan Relay 1 to jumper 30 and 87.

d. Cooling fan high-speed requires jumpering 30 and 87 of all three relays.

Note: There's a small problem as Cooling Fan Relay 3 is not located in a relay or fuse box - its installed in a wiring harness - basically between left-side (drivers) headlight and battery box. (I can take a photo if it'll help).

[fdryer]

14ozs is half of the full amount. The rest is injected with the engine running at higher rpm (2k) so the compressor has greater suction. Pm sent.

[Fool_4]

Which compressor is it I go by? L61 or L66?

I see the sensor is shown as a 3 wire device, didn't notice that last night.
Looks like my main objective now is going to be to verify what is going back to either the ECM(L61) or PCM(L66) on either the rd/blk (L61) or the wht (L66).
Thanks for the drawings, they will no doubt help more than a little.

[Fool_4]

Originally Posted by far2grumpy

I'm not sure if you PM'ed fdryer for data so I'll attach two thumbnails - one with AC interlock wiring and the other is cooling fan wiring.

The cooling fans run at two speeds ...

a. If PCM wants low speed only - Cool Fan Relay 1 is latched and both fans run in series using 6 volts each.

b. If PCM wants high speed - all three relays are latched and each fan runs from 12 volt B+.

c. You could run both fans low-speed by removing Cool Fan Relay 1 to jumper 30 and 87.

d. Cooling fan high-speed requires jumpering 30 and 87 of all three relays.

Note: There's a small problem as Cooling Fan Relay 3 is not located in a relay or fuse box - its installed in a wiring harness - basically between left-side (drivers) headlight and battery box. (I can take a photo if it'll help).

Thanks for the fan info, I already saw the floating wiring harness relay and wondered what it was about. I had been in the relays for the fans doing the 30-87 jump and jumping one in the relay box, I didn't hear the fans, but felt the hot air. Jumping the other I just got one fan full on, your explanation makes total sense in light of observations.
What would us orphaned Saturn owners do without you guys?
Thanks LOADS!

[far2grumpy]

Originally Posted by Fool_4

Which compressor is it I go by? L61 or L66?

I see the sensor is shown as a 3 wire device, didn't notice that last night.
Looks like my main objective now is going to be to verify what is going back to either the ECM(L61) or PCM(L66) on either the rd/blk (L61) or the wht (L66).
Thanks for the drawings, they will no doubt help more than a little.

3.5 is L66.

See thumbnail for sensor explanation ... the pressure values listed are for the 3.0 compressor but should give you an idea of range.

OK - disregard values above - here's cut-n-paste from the 3.5 section:

L66/3.5L

The A/C high side pressure is more than 2929 kPa (495 psi). The clutch will be enabled after the high side pressure decreases to less than 1376 kPa (200 psi). A/C low side pressure is less than 2706 kPa (39 psi). The clutch will be enabled or will allow engagement again after the low side pressure increases to more than 2941 kPa (43 psi).

[Fool_4]

Ok do you guys see any trouble if I just installed a pot to get me a voltage from 0-5VDC, just to get the system charged and all?

One more sensor, we have not discussed, seems to be a thermistor heat sink compounded into a little hole in the side of the TXV. I made sure and put extra compound into the hole on the new TXV before installing this sensor. Is it also possible that this sensor could be errant and the cause of the compressor lock out as well? I am not seeing this "other" sensor on any diagrams.
Thoughts?

[far2grumpy]

Originally Posted by Fool_4

Ok do you guys see any trouble if I just installed a pot to get me a voltage from 0-5VDC, just to get the system charged and all?

One more sensor, we have not discussed, seems to be a thermistor heat sink compounded into a little hole in the side of the TXV. I made sure and put extra compound into the hole on the new TXV before installing this sensor. Is it also possible that this sensor could be errant and the cause of the compressor lock out as well? I am not seeing this "other" sensor on any diagrams.
Thoughts?

I was thinking earlier that two series 1.5 batteries would probably be in range the PCM wanted to see ... but a pot makes more sense ... you can use the existing +5 and ground wires and vary input on pressure sense line as needed.

I've attached three thumbnails ... one for TXV sensor data ... another depicting where TXV data is sent to BCM ... and another depicting the AC request signal starts on blower drawing and is also sent to BCM. I believe you could assume if the TXV data is within range - the BCM would forward the AC Request signal to the PCM.

Since the PCM is not happy with line pressure the brakes are applied.

[Fool_4]

Thanks, I am going to go back out in the sun and start todays troubleshoot. It looks like I have all the info I should require to get this going now.
Will post my eureka moment, soon I hope...

[Fool_4]

Far2Grumpy, what is the avatar your using? Is that a border collie? I have a customer that breeds them, and your avatar sure does, to the untrained eye look like one.

[far2grumpy]

Originally Posted by Fool_4

Far2Grumpy, what is the avatar your using? Is that a border collie? I have a customer that breeds them, and your avatar sure does, to the untrained eye look like one.

She's an Aussie Shepard - lovable but has no ears (does not mind). She thinks shes smarter than a border collie.

A very poor choice for an old coot like me. Is constantly looking for something to do and hates to be alone ... one of breed nicknames is Velcro dog.

She can - and does - herd kids, other dogs and some adults.

It stopped being funny (for me) a year ago - we've had for 13 months.

My wife read a book with quote - get an Aussie and you'll never go to bathroom by yourself. Its true - securely latch the door or beware.

[Fool_4]

Well it's a cute doggie at any rate, don't know about the constant need for closeness ,might tend to annoy.
I got my AC to run, with a pot connected as per diagram and dialed into 1.8V. There is one other issue that I found worrisome, the scent of the citrus based flush I used flushing the system could clearly be smelled when I disconnected the gauges. Knowing the sense of smell to be 10,000X the sense of taste, is it possible that this is ok and just representing a trace amount of residue?
Should I panic and break it all down again?