98 Monte ABS, HVAC, Air filter

The ABS light on the dash has been on for awhile. A popped tire, I think, tore the RF ABS harness. I was too lazy to fix it right away. I had the same problem on a '92 Lumina--RF sensor harness open to road splash.

What happens is that water gets inside the insulation of the broken wires, and corrodes the wire down towards the sensor, and up towards the engine compartment. The corroded wire can't be soldered, solder won't stick to it. And it's a mess to clean off with flux and heat. If the wire corrosion is only a few inches, you can cut the section out and splice to clean wire. In this case, the wire was rotted all the way down to the sensor connector, and all the way up to the engine compartment connector. I disconnected that section of the ABS harness at both ends, and opened it up for inspection. There was "no hope", so I visited my favorite Treasure Yard and grabbed a replacement harness complete with the bulkhead grommet that goes through the strut-tower.

Wheel sensor end of ABS harness. Note corroded, blackened wire

http://hbassociates.us/Monte_ABS_01.jpg


Engine compartment end of ABS harness, almost to the strut-tower grommet. Wire is still corroded black.

http://hbassociates.us/Monte_ABS_02.jpg


Replacement harness from Treasure Yard, including grommet and retainer clip where it goes through the strut tower

http://hbassociates.us/Monte_ABS_03.jpg

ABS repair entirely successful, I didn't even have to clear any codes. I got in, drove it, and the ABS warning light turned itself off. Scan tool shows all four wheel sensors providing the same vehicle speed to the ABS when I drive.


Next repair was due to a plugged air conditioning drain nipple (Duckbill). The condensation wouldn't drain from the evaporator box. When I'd take a left turn, the condensation would slosh into the blower fan and make noise, and also produce "fog" from the A/C vents. If I'd gone under the car, found the silly little drain nipple very near the exhaust downtube, pulled it off and cleaned it, the water wouldn't have corroded the blower-motor resistor pack.

Drain nipple, cleaned-out. Pulling this off the stub-pipe on the firewall released about a quart of water--condensation from the A/C evaporator.

http://hbassociates.us/Monte_HVAC_01.jpg

By the time I got around to attending to this, the resistor connector had corroded so bad I couldn't get it off of the resistor pack, and there was no current flow through the resistors--so the fan speed switch had "off", "off 1", "off 2", "off 3" and "High".

http://hbassociates.us/Monte_HVAC_02.jpg


Corrosion extends to the underside of the connector. I couldn't get the connector to release--it's corroded together.

http://hbassociates.us/Monte_HVAC_03.jpg

Getting at the resistors is a bitch. First I removed the interior hush panel on the far right side under the dash (two barbed connections hold it in place) and then there's three screws in the resistor pack WAY forward by the firewall, to the side of the blower motor. The resistor pack faces "up", so there's almost no tool clearance to put a 7/32 socket on the screws next to the firewall. Once I removed the corroded resistor pack I clipped the wire harness a few inches from the connector. Again, the Treasure Yard supplied a replacement resistor pack and connector, with eight inches or so of wire harness.

http://hbassociates.us/Monte_HVAC_04.jpg

I connected the replacement harness to the vehicle harness using a 4-prong weatherpack connector pair. I could have soldered the wires directly, or crimped them without a connector.


Lastly, I decided that perhaps I should check the engine air filter. No special reason, but I know I haven't done it in years. Pulled an entire mouse-nest out of the filter box. Car would still go 70 mph +. There really didn't seem to be a problem with performance--but perhaps the next drive with a new filter will show improved performance I didn't know I was missing.

http://hbassociates.us/Monte_AirFilter_01.jpg


I gotta stop procrastinating on vehicle maintenance. Each of these issues was made worse by not taking care of things right away. Next up: replace fuel filter, inspect spark plugs 'n' wires, inspect/replace radiator cap and coolant hoses.

I always cut that drain hose nipple off-- only GM "W" cars have the nipple, all other GM cars are just a straight hose--and they don't plug up....Just sayin"

All that mouse house material might have made for a pretty effective pre-filter.

Next Up:

Car wouldn't crank one afternoon. Slapped a new battery in it, Dear Old Dad replaced the battery last in 2010, according to the date sticker on the Die Hard Gold battery I removed.

I'm not sure the thing is worth adding water to and re-charging. I have no faith in a nine-year-old conventional wet-cell battery, especially with one very low cell. $160 to NAPA for a replacement battery.

While I'm dicking with the electrical system, I connect a scan tool just for giggles. My O2 sensor cross-counts are in the single-digits--"0" to "7" mostly. Well, yeah, I guess that makes sense since I'm sure the O2 sensor is original, ancient, and lazy. The thing is old enough to buy liquor. Mind you, the car has less than 35,000 miles on it.

I'm not looking forward to ripping that sensor out. I just pulled four O2 sensors out of my '97 K2500, and three of them needed an oxy-acetylene torch to get them to turn. All of them damaged the threads in the pipe they screwed into, so I had to clean up the threads before I could put the new sensors in. It'll maybe be harder on the Monte, due to the sensor being tucked up higher and closer to the engine. There'll be very little room to get the torch in there.

Wish me luck.

Luck? For me, "luck" with O² sensors is usually spelled H-E-A-T and is sometimes assisted with P-R-A-Y. But it sounds like you already know the drill.

Keep at it. It seems that you might just have this thing spiffed up and ready for winter.

Since this forum has had no postings in forever, I thought I'd update my thread.

Swapped the pre-catalyst O2 sensor. No drama, no problem. Screwed right out. New sensor has much faster response.

A/C was very weak when I started using this car this spring. Dumped about a pound of refrigerant into the system--now the pressures look better and it cools almost like it should. I still think it's a little weak; but not horrible. I remember REAL air conditioning--the ancient GM POA system, which could blow 32 degree air along with occasional ice crystals out the dash vents. The CCOT system can't hold a candle to that. So all CCOT systems seem "weak" to me.

I may dump some more refrigerant in it. The pressures I achieved already were on the low side of the "normal" range.

Far as I know, this is the first time the A/C has had refrigerant added since the car was new. Dear Old Dad was too cheap to pay someone to do it; and I didn't add any while he owned the car.

You're not alone in the world and some of us are listening. Still keeping my old 99 GTP running. Its A/C needs some attention. I know it leaks refrigerant but I don't think the vent controls are working right. Gonna get that figured out first...when I have time.

i concur on the AC systems of olde.. could pump R12 or R22 Freeze into a GM and see small crystalline snow flakes (like the button said) coming out of dash vents; even in texas!.. those days are gone..

Found squatters in the air cleaner of my '92 Lumina 3.4.

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