"AC Problem" turned out to be something else
Posted: Thu Jun 01, 2023 7:32 am
"AC Problem" turned out to be something else. 1988 Mazda truck, B2200, mine since 1994.
Last month when 90F outside I noticed that my AC wasn't working properly (and only 2 more months until summer here in Arizona); the LED light I'd added parallel to the compressor wire was lit on the dashboard, but didn't seem as bright as it had been. So once the AC started blowing warm, I pulled over and the AC clutch was not engaged, even though it was getting voltage according to the LED dash light. I tapped on the compressor drive plate (carefully) with my softball bat, and the AC clutch pulled in. So on my drive home was figuring I might need to remove an AC clutch shim from the Sanden 708 I'd purchased brand-new from Tim/AC Kits in 2014, and figuring I could do that with compressor remaining installed (like I did on my '98 Frontier in 2019).
Once I got home, I measured 11 volts across the battery terminals with engine running, but my charging warning light had not come on, so I knew alternator wasn't charging. I did a cranking load test, as voltage across the battery was under 5 volts (needs to be 9.6 volts or greater). So I figured that the AC clutch was simply not getting enough voltage to engage (see Note at end of post). A month ago I had my battery checked by both O'Reilly and Autozone across the street from each other, same day, and one told me battery was OK and the other said battery bad. So I was off to Walmart to trade in my 2-year old Everlast Maxx battery, which was 2 years old and was a free warranty replacement, so I got pro-rated $60 off on the brand-new battery.
After installing the battery, the alternator still wasn't charging, and still no warning light; so I figured it was time to replace the 35-year-old factory alternator. I took the old alternator to O'Reilly for testing, tested bad. I'd had good luck with O'Reilly lifetime alternator in my '98 Frontier, so I ordered one in for my B2200. That arrived a day later, and I installed it and now everything is working, including the charge light and voltage across the battery or in my lighter socket; with engine running is about 14 volts.
I'd been having intermittent "failure to crank the engine" symptoms for 2 years (why I got the free battery replacement in 2021), but hadn't had any charging light warning appear on the dash; but now for sure the charge light does show before I start it, not sure if that happened before I replaced the alternator. So I'm not expecting any more non-cranking situations either.
Note: in the early 1990s, driving Mrs. Cusser and some co-workers back to a work outing at saguaro Lake in our 1984 Jeep Cherokee, the AC vent temperatures rose just before we arrived there. After the cruise/dinner, I started it up and noticed a low reading on its voltmeter, but no charging light was on. So that was my first experience with bad alternator causing failure of an AC clutch to engage. And I remembered that when I measured the output of the alternator on that 1988 Mazda truck.
Last month when 90F outside I noticed that my AC wasn't working properly (and only 2 more months until summer here in Arizona); the LED light I'd added parallel to the compressor wire was lit on the dashboard, but didn't seem as bright as it had been. So once the AC started blowing warm, I pulled over and the AC clutch was not engaged, even though it was getting voltage according to the LED dash light. I tapped on the compressor drive plate (carefully) with my softball bat, and the AC clutch pulled in. So on my drive home was figuring I might need to remove an AC clutch shim from the Sanden 708 I'd purchased brand-new from Tim/AC Kits in 2014, and figuring I could do that with compressor remaining installed (like I did on my '98 Frontier in 2019).
Once I got home, I measured 11 volts across the battery terminals with engine running, but my charging warning light had not come on, so I knew alternator wasn't charging. I did a cranking load test, as voltage across the battery was under 5 volts (needs to be 9.6 volts or greater). So I figured that the AC clutch was simply not getting enough voltage to engage (see Note at end of post). A month ago I had my battery checked by both O'Reilly and Autozone across the street from each other, same day, and one told me battery was OK and the other said battery bad. So I was off to Walmart to trade in my 2-year old Everlast Maxx battery, which was 2 years old and was a free warranty replacement, so I got pro-rated $60 off on the brand-new battery.
After installing the battery, the alternator still wasn't charging, and still no warning light; so I figured it was time to replace the 35-year-old factory alternator. I took the old alternator to O'Reilly for testing, tested bad. I'd had good luck with O'Reilly lifetime alternator in my '98 Frontier, so I ordered one in for my B2200. That arrived a day later, and I installed it and now everything is working, including the charge light and voltage across the battery or in my lighter socket; with engine running is about 14 volts.
I'd been having intermittent "failure to crank the engine" symptoms for 2 years (why I got the free battery replacement in 2021), but hadn't had any charging light warning appear on the dash; but now for sure the charge light does show before I start it, not sure if that happened before I replaced the alternator. So I'm not expecting any more non-cranking situations either.
Note: in the early 1990s, driving Mrs. Cusser and some co-workers back to a work outing at saguaro Lake in our 1984 Jeep Cherokee, the AC vent temperatures rose just before we arrived there. After the cruise/dinner, I started it up and noticed a low reading on its voltmeter, but no charging light was on. So that was my first experience with bad alternator causing failure of an AC clutch to engage. And I remembered that when I measured the output of the alternator on that 1988 Mazda truck.