Service Vehicle Light = A/C not working

Hello - this is my first post. I hope I'm doing this right. I searched to see if there were any previous posts about this problem and didn't find any that were exactly the same.

I hope you'll all excuse me for not being a Grand AM enthusiast. My husband has a 2001 (I don't know if it's SE or GT or any of that. I think it's 4 cyld.) Anyway, he bought it used because it was a good deal and he liked the way it looked, low miles, etc. We've had it a few years without major incident. Lately I've been searching the Internet because of our Grand AM's wacky behavior and it seems all/most Grand AM's are "quirky" (that's putting it nicely.)

Anyway, the specific problem we're having right now is the Service Vehicle (NOT ENGINE), light comes on upon start up - but not every time. Only sometimes. It's very unpredictable.

You start the car and the instrument panel doesn't light up right away - that's how you know it's going to happen. And then DING DING DING (chimes), the Service Vehicle light is on. When it's on the A/C does not function at all.

When this first started happening we never checked the A/C so not sure if it's always been connected or if that's a new thing.

When the SV light started coming on sometimes last month we turned to the manual which mentions Daytime Running Lamps or something, (I'm not a car person)... Anyway, my husband and I checked every single bulb in the head lights and tail lights and everything was fine. He replaced all the ones in the headlights just in case though.

We read online about how to reset the SV light by pumping the break or something and disconnecting the battery, tighetening the fuel cap, etc. We tried a couple methods. Anyway - none of those were long lasting solutions.

Then my husband noticed his carpets in the rear were wet so I researched that thinking it might be connected. It was not. We pulled the carpet out and used some kind of autmotive welding caulk to close up some areas where rainwater was getting splashed up in there when the vehicle is driven. That problem is completely solved.

My husband took the car to Pontiac who hooked it up but said they can't find anything because at that time the SV light wasn't on. (And it doesn't stay on so we can't get any error code or whatever.)

Lastly, my husband noticed this week when he drives on the highway the car seems like it's not shifting gears well at higher speeds or is losing power. (He wasn't sure how to explain it to me as English is his second language - and I haven't experienced it yet.)

Any tips, hints, ideas? Thank you in advance.

[rixGAphx]

First off, :welcome: to GAOC!

4-cyl, automatic tranny; 2001, 6-yrs old, about 60,000 miles?
Random SVS light, no SES light.

1. So, you had a floor-leak problem, now fixed as far as water intrusion is concerned; it might still relate to the SVS light, tho.
More on this later.

2. Low-power/poor shifting at higher speeds:
The engine operation and the tranny's shifting is controlled by the PCM (Powertrain Control Module, GM's name for the engine/tranny 'puter).
It's pretty sophisticated, and senses when just about anything is wrong; then sets a code and illuminates the SES icon.
The PCM does NOT monitor: Fuel pressure, vacuum hoses for the powerbrakes and Htr/AC, and many internal transmission problems.
As a first step, considering the vehicle's age and milage, I would get a tranny fluid change, air filter change, and fuel filter change.
These are: Recommended at 60k miles, necessary for long-term vehicle reliability, not monitored by the PCM, and possible culprits.

3. Random SVS Light: This code comes from the BCM (Body Control Module, the 'puter that controls everything but the engine/tranny and the ABS).
It is located in the vehicle's side, behind the plastic panel alongside the front passenger's right foot.
Usually when it illuminates, it is warning of a burned-out lamp.
You've already done step one, which was to check the lamps. But you must check ALL the exterior lamps, including turn signals, side makers, back-up, braking, and parking.
Step 2: Check the bottoms of the sockets, especially the taillight sockets, for internal corrosion of the bulb contacts. Clean as required.
Step 3: Check the little ground wire, from the BCM to a nearby piece of metal. This might have gotten rusted/corroded by the previous leak. Clean the corrosion, or run a new ground.
Step 4. You say the AC won't work everytime the SVS light comes on. But then you hint that it doesn't ever work??
Anyhow, if the AC is low on refrigerant pressure (r134a, the modern substitute for old-fashioned 'Freon' r-12), then the AC will not work. I don't know if it illuminates the SVS ight or not.
Did you know that the BCM turns the AC 'on' at odd times? When you have the controls set to 'Defrost', the AC is 'on' (to act as a dehumidifier).
The moisture that the dehumidifier sucks out of the air drips into a 'catch pan' under the AC fan box. There's a drain tube from this catch pan out thru the firewall to drip onto the ground under the passenger's feet.
If the drain tube is clogged, the pan will overflow into the cabin, and the water often flows under the carpet.
Finally, the Htr/AC have little damper doors inside the ductwork. They control which direction the aire flows, and they are operated by vacuum diaphragms via tubes from the Htr/AC control panel.
The control panel gets that vacuum from the intake manifold.
SOOOOO, inspect the vacuum lines under the hood; especially the tubes that connect to the vacuum reservoir (black plastic grapefruit-sized and shaped ball under the battery).
A vac leak would cause poor/no AC operation, possibly an SVS light, and possibly the rough-running and shifting.

As to the water on the floor:
IIRC, the only wires on the floor are for the seat belt indicators and power seats, if you have them).
It's possible that the water got into an under-carpet connector, or that the wires were disturbed by the drying procedure.

Finally, are there any OTHER 'gremlins' with this car, that you haven't mentioned?
Specifically: seat belts, power windows, power locks, remote trunk release, etc?

Random electrical faults are THE most difficult problems to diagnose and correct, so this may take a while.

Hope this helps.
-Rick

Dear Rick,

WOW. Thank you so much. I'm going to have to read this over and over again until I understand it all. LOL. I'm printing out to show my husband and will definitly get back to you and let you know what we find/don't find, etc.

As for the AC - Sorry I wasn't clear. The AC works just fine as long as the SVS light is not on.... I was just trying to say - we didn't notice the AC didn't work when the light came on at first. It took us a couple weeks to realize it.

As for the mileage - I believe we're in the 70 something range. I'll get back to you. (Husband has the car right now). Will also let you know about "other gremlins". Have to ask my husband about that, too.

Thanks again. I'll be in touch!

[Conley]

Originally posted by lopezfamilymail
Dear Rick,

WOW.

Yeah, I'd have to agree with you on that one. Rick is pretty much THE MAN when it comes to explaining and solving problems in detail. Very knowledgeable that guy is. :bow:

Good luck with your problems. Hopefully it's something Rick mentioned so you can sort it out and fix it. Maybe one day we'll convert you to a Grand Am enthusiast. :)

[SE2000]

Tee, if memory serves me, there is a module located under the passenger seat. Since you had water on the floor there, you could have corroded connectors. Look under the front passenger seat for a module (black box) and check it out. I think you have to disconnect the battery before you pull the plugs. The passenger seat can be removed by moving it all the way forward and removing the 2 bolts at the back and tilting it up. If it's not there, ignore above message

Rick -

1. More details about the car. It has 77,000 miles on it. It does not have power windows but does have power locks. (Forgot to check the seats. I'm almost sure they are NOT power seats). Husband says no other "gremlins" he has noticed.

My husband already recently changed the air filter and is going to try changing the fuel filter this weekend. He's a little scared to get the tranny fluid changed as my father told him if someone does it wrong they can really screw up your car. (My dad's experience, I suppose.) Anyway, he'll have the tranny fluid changed possibly if changing the fuel filter doesn't help.

2. Last night we attempted to locate the BCM. We found some kind of fuse box on the passenger side which we never knew existed. You can only access it with the passenger door open as it's on the side of the dash. Is this the BCM? Regardless, we looked around in there and didn't see any rusty wires. We also pulled off some plastic guard and pulled back carpet near the front passenger seat and found various wires and none of those were rusty.

3. We rechecked all the bulbs on the car and they're all working fine. We checked the sockets, bulb contacts for corrosion and they were fine there as well.

4. So at this point I think we are going to change the fuel filter and inspect the vacuum lines. Hopefully that will be the solution.

Thank you again for using your knowledge to help others. Not to get sappy or anything but my husband works hard as a welder to provide for the family. I'm a stay-at-home-mom to our 2 sons because I think it's really important to be there for the kids. We aren't poor but we aren't rich and any little vehicle repair we can do on our own helps our tight budget. So again, thank you very much.

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Conley - Thanks for the wish of good luck. I don't know about becomming a Grand AM enthusiast but I am becomming a Rick enthusiast ;) LOL.

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SE2000 - Ok - I will check that, too. I didn't even know we could remove that seat. Thanks.

[rixGAphx]

Vacuum Leaks:

There are TWO *main* 'vacuum' systems under the hoods of GA's (and most other modern cars, say '85 and newer):
1. Emissions-related - For recovery of gasoline vapors from the intake manifold after the engine is turned off.
* By federal law, there is a diagramatic decal of this system under the hood on the passenger side; sometimes on the hood or firewall, for the GA it's on the right front strut tower.
* For all US and CN cars '96 and newer, this entire system is well-monitored, and reported as flashing Check Engine/SES light and scanable thru the OBD-II port. Faults in this system include loose/faulty gas tank cap.

2. Non-emissions - For operation of vacuum-powered car accessories. This system is NOT monitored, and faults here will have assorted consequences but prolly won't cause a SES (or SVS) code.
For the GA, these are:
* Power Brake Booster: A single 1/2" black rubber hose that runs directly from the intake manifold to the brake booster (black cake-pan type can on the firewall, to which the master cylinder mounts).
* HVAC (Heating, Ventilating, and Air Conditioning) controls: A single 1/4" black rubber tube that changes to a hard plastic 1/8" tube; runs from intake manifold down toward the vac reservoir under the battery, where there's a 'TEE'.
Depending on the engine and car year, there's a tube that runs across the 'open-space' from the engine to the vac reservoir; this tube is easily disconnected accidently, and you can't see it unless you really look for it.

3. Minor 'Vacuum systems' on the GA:
a. Auto Tranny: On the front of my autotranny, there was a vacuum modulator; I don't know how it worked, since I thought the tranny was fully-hydraulic/electric. But, it was there.
b. Positive Crankcase Ventilation: The V6 engines have a PCV valve in the front valve cover, that has a hose connecting to the intake system for suction of oil vapors.
As I understand it, most (or all?) GA 4-cyls do NOT have this PCV system; they use something else to accomplish the same task.
c. Fuel Pressure Regulator: On the V-6's (and maybe the 4-cyls, I dunno), there's an FPR on the front of the fuel rail.
It receives some vacuum from some control valve on the intake manifold.
Again, these systems are NOT monitored and won't throw codes.
* * *

Easiest way to check for vacuum leaks is:
1. With engine 'off', visual inspection under the hood, with good lighting.
Basically, all nipples on the intake manifold should have tube (or a facory plug for a non-used port), no tubes should be dangling, all rubber hoses and nipples should be free of age cracks, and all tubes should be free of kinks, heat-blisters, and other damage.

2. With car in driveway (not an enclosed garage) and engine 'on', carefully do the following test. Remember the spinning serpentine belt and pulleys, and that the radiator electric fans might come 'on' at any time.
* At each vac port, tube, junction, and device, spray a little 'Winter Starting Fluid'.
If there's no leak, the stuff will dissipate into the air.
If there's a leak, the stuff will be drawn into the intake and burned in the cylinders; the rpm;s will rise immediately, and rough-running will *usually* smooth-out temporarily.
3. A vac leak *might* occur at the HVAC control panel, or at one of the ductwork dampers deep under the dash.
Just pray this isn't the case, as they are complete PITA's to access, diagnose, and fix.

* * *
Tranny Fluid.

Your father was right about the tranny-fluid change: It can be done wrong with disastrous results.
But his caution needs some explanation, and that will asuage your worries.

Since autotrannies first became mainstream in the mid-'50's they have had the fluid changed every so often.

1.Fluid Change: It's necessary, easy for a shop, and relatively cheap and idiot-proof.
There's also a filter in the tranny pan, and that needs either cleaning (modern filters) or replacement (older units, say pre-'90).
Costs about $50 at a major reputable shop, if you get their coupon or once-monthly special
This 'Fluid Change' drains about 50% of the old fluid out, and replaces with new. The remaining 50% can't drain 'cuz it's 'stuck' behind one-way valves and pumps and such.
No matter; just change 50% every 30-50k miles, and you always have enough 'fresh' fluid.

2. Fluid Flush: About the late '80's, a pressurized system was sold to shops, so they could pressure-pump 100% of the old fluid out of the system, and introduce 100% new.
Great, huh?
Unfortunately, some of the machines (or technicians) used too MUCH pressure, and/or the rubber seals in high-milage cars were weak with age. The result was that a week or a month or two after the tranny 'power flush', a previously non-leaking tranny suddenly leaked big-time and needed a complete rebuild for several thousand $$$. Thus the true rumors that have concerned your father.

3. Present-day Fluid-Flush Systems:
Many systems in use now don't even have there own pressure pump, just some suction equipment. So they can't even produce damaging levels of pressure.
Rather, they depend upon the tranny's own internal pump to force old fluid out the cooling line (at the radiator) and suck-in new fluid at the same place.
You want to go to a major reputable shop that uses this technique.

4. Your 5-yr old tranny with 70k miles is in FINE basic condition to receive a Fluid-Flush of the non-pressurized type.
Or, you could just do TWO of the simple 'Fluid Changes', about 2-8 weeks apart. This would produce [50% + (50% x 50% = 25%)]= 75% fresh fluid.

The car is past-due for this procedure. Depending on how hard the vehicle was/is driven, and under what conditions of heat and dust, there is risk real trouble, damage, and/or wear if not changed soon.

Good luck,
-Rick

GAOC people are the BEST!!
This is a very supportive bunch, always willing to share in a positive and friendly manner.
Thanks for the kind words.

[vegito]

I can't seem to figure this one out. I've had the problem for awhile now, and have tried changing bulbs, (all bulbs are working), as well as bulb grease and wrapping all wiring harness wires with electric tape to ensure they are insulated... I found Rick's "fix all" in several posts that I will be trying tonight, as well as taking a look at the ground wire under the hood. Any other suggestions? Sorry to be posting in such an old thread, but this is the first real explanation I've found online of my problem.

Thanks!!!