AC Failure & Restoration questions

Pete_89T2 · 05-08-2017, 02:04 PM

One other thing I forgot to add. While removing the stock aux E-fan to get the condenser out, I found out why it was so damned loud & vibrated a bit much.... Turns out 1 of the 5 plastic fan blades was busted off, and the other 4 blades had various chips & cracks. So it was way out of balance.

Mazda still sells a replacement fan blade for it, at like $50. I'm thinking I can just get a universal 9~10" E-fan off of Ebay for around $20~$35, fab up a quick mounting bracket or reuse the existing stock fan frame and get better performance.

Pete_89T2 · 08-22-2017, 01:53 PM

I just realized I forgot to post up my results after finishing this AC project. Short story is the duster gas (aka. R152A or HFC-152A) works about as well in my restored FC A/C system as the old R12 did.

The 1st reman compressor I got was probably damaged in shipping, in that the mag clutch would sometimes stay engaged even after it was de-energized. The company I bought it from (see previous posts) replaced it under warranty, but that meant I had to R&R the compressor, evacuate/vacuum the system & recharge it again. Good thing R152A is dirt cheap - $11 for a 4 pack of 10oz cans at Walmart.

The step by step procedure I used for evacuating & charging the system with R152A is within in the first 40 or so posts here from the other forum:

https://www.rx7club.com/1st-gen-arch...gerant-997918/

The best result I got was about 7*C (= 44.6*F) temperature from the center vents at max cooling. According to the link, it should take in about 2x full 10oz cans of duster gas, but I couldn't get the system to ingest more than maybe 1-1/2 cans. Not sure why, as I followed all the tips suggested in the link to get the last can in. So perhaps my system is slightly under charged, or perhaps the new expansion valve I got, which *I THINK* is calibrated for R12, being it's an OEM replacement, might not be optimal for using R152A.

For my busted auxiliary E-fan, I found a nice 10" universal fan on Ebay for about $18 that I was able to easily adapt to fit the stock e-fan bracket. No more noise & crazy vibes when the fan kicks in.

Anyway, I'm happy with it!

t_g_farrell · 08-22-2017, 03:40 PM

Hey, that sounds great. I think I remember it always taking less duster gas
than 134a but not sure about how the amount compares to R12.

Pete_89T2 · 08-23-2017, 07:06 AM

The OP from the other forum says the charge by weight for R152A is 20~22 oz, based on molecular weight. Since it sucks to wade thru 40-ish posts to find relevant info, I packaged the OP's instructions into a single handy PDF file - see attached.

There may be another reason why I couldn't get that full 2nd can in.... In order to retain my AC & PS with the FFE crank trigger kit, Angry Stig came up with a brilliant solution using a backwards mounted spare FC Alt/WP/air pump drive pulley & some AL spacers. Since those pulleys are smaller in diameter than the stock AC drive pulley, I'm now under driving my AC a wee bit. So it is very possible that when I was charging the system at 2000~2500 RPMs per the instructions, maybe I should have been revving it higher to draw that last can in?

08-22-2017, 03:40 PM	#18
t_g_farrell Waffles - hmmm good Join Date: Aug 2008 Location: Huntersville, NC iTrader: (0) Posts: 757 Rep Power: 0	Hey, that sounds great. I think I remember it always taking less duster gas than 134a but not sure about how the amount compares to R12. __________________ 1980 GS stockport, Fat Nikki, RB Dual Facetfuel pumps, Holley regulator, RB Street port exhaust, 2GDFIS, MR2 MK I electric fans, 2G strut bar, relayed fans, lights and fuel pump, LEDs Project Fat Nikki Budget 12A rebuild Video setup < $30.00

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05-08-2017, 02:04 PM	#16
Pete_89T2 Lifetime Rotorhead Join Date: Apr 2010 Location: Elkton, MD iTrader: (1) Posts: 874 Rep Power: 15	One other thing I forgot to add. While removing the stock aux E-fan to get the condenser out, I found out why it was so damned loud & vibrated a bit much.... Turns out 1 of the 5 plastic fan blades was busted off, and the other 4 blades had various chips & cracks. So it was way out of balance. Mazda still sells a replacement fan blade for it, at like $50. I'm thinking I can just get a universal 9~10" E-fan off of Ebay for around $20~$35, fab up a quick mounting bracket or reuse the existing stock fan frame and get better performance.

08-22-2017, 01:53 PM	#17
Pete_89T2 Lifetime Rotorhead Join Date: Apr 2010 Location: Elkton, MD iTrader: (1) Posts: 874 Rep Power: 15	I just realized I forgot to post up my results after finishing this AC project. Short story is the duster gas (aka. R152A or HFC-152A) works about as well in my restored FC A/C system as the old R12 did. The 1st reman compressor I got was probably damaged in shipping, in that the mag clutch would sometimes stay engaged even after it was de-energized. The company I bought it from (see previous posts) replaced it under warranty, but that meant I had to R&R the compressor, evacuate/vacuum the system & recharge it again. Good thing R152A is dirt cheap - $11 for a 4 pack of 10oz cans at Walmart. The step by step procedure I used for evacuating & charging the system with R152A is within in the first 40 or so posts here from the other forum: https://www.rx7club.com/1st-gen-arch...gerant-997918/ The best result I got was about 7C (= 44.6F) temperature from the center vents at max cooling. According to the link, it should take in about 2x full 10oz cans of duster gas, but I couldn't get the system to ingest more than maybe 1-1/2 cans. Not sure why, as I followed all the tips suggested in the link to get the last can in. So perhaps my system is slightly under charged, or perhaps the new expansion valve I got, which I THINK is calibrated for R12, being it's an OEM replacement, might not be optimal for using R152A. For my busted auxiliary E-fan, I found a nice 10" universal fan on Ebay for about $18 that I was able to easily adapt to fit the stock e-fan bracket. No more noise & crazy vibes when the fan kicks in. Anyway, I'm happy with it!