I've got a new to me '90 Miata with a FMII Hydra setup. As far as I know, the AC hasn't worked in a long time. I got it recharged and converted to R134A and it cools great at idle. But, with any throttle input at all, the compressor quits and there's no cooling. Driving down the road, I get no cooling--only coasting down hills and at stop lights.

From what I read, 90-93 TPS's are basically an on/off switch, which I also see in the Hydra software (0 or 100% throttle only).

From what I know about other (newer) cars, the ECU typically cuts the AC during wide open throttle. How does it work with the 90-93 Miata's setup with the Hydra?

I don't see anything in the Hydra software about AC control.

Does the Hydra use the TPS or only the MAP sensor?

Any ideas what I should try?

 

I deleted all my hydra installs, but there is a setting to shut off A/C at near-WOT.

it's probably either under settings or Outputs

 

Thanks. I looked a little deeper and found it under INJ8 output. See attached screenshot. Should I just set this to 100% so that it never disengages while the AC button is on? If I want maximum power, I'll turn the button off.

 

sure...

 

well, I changed it to 100%, downloaded to ECU, and tried it. No change. I uploaded from ECU to verify its set at 100%, and it is. Any suggestions on what to try next?

I attached my .s20 file.

Note: this forum wouldn't accept a .s20 file, so I changed the extension to .zip. It is not zipped. Please change it back to .s20 before trying to use.

 

call flyin' miata (800)359 6957
Ask to talk to Jeremy

Yes, the hydra has a setting to cut AC at WOT. That setting probably needs to be turned off with the 1.6 ON/OFF TPS. Jeremy should be able to tell you where its at before you can say 'exorcist' 3 times fast.

 

thanks, I called him and he's never heard of the issue before. He's sending a wiring diagram so I can wire in a variable TPS from a 1.6 auto. Also, I'm supposed to make sure there hasn't been any hacking done to the fan wiring.