AboutMp2 Expertise I prefer to answer questions relating to the Miata since this has been my area of specific
expertise since 1991. I can answer questions relating to the other Mazda models however
some limitation of expertise may reduce my accuracy.
Experience Mazda technician since 1987, shop owner and specialty are regarding the Miata since 1991 covering mechanical, electrical, trim and body. Specializing specifically in drivability concerns.GKHS 1985, BVC 1987, MNA 1989, ASE Master Technician Mechanical 1995, ASE Master Body/Paint/Collision 1996
Education/Credentials GKHS 1985, BVC 1987, MNA 1989, ASE Master Technician Mechanical 1995, ASE Master Body/Paint/Collision 1996
Question Noticed more at stop lights or when engine is idling...a bind or bog down in engine...noticable loss of pick up speed while compressor is engaged.
Answer The AC compressor can take as much as much as 10 HP from your cars available power. This in addition to what the Alternator, Power Steering Pump and Water Pump require to operate. The 1.6 generates 110HP at peak RPM. That was in 1992.
Factors, like ambient temperature, idle and timing adjustments, intake restriction and exhaust restriction can all play a role in how much these accessories affect the feel of your Miata.
It's not likely that the compressor itself has anything more to do with power loss, it just is amplifying it because it draws the most power of all the ancillary items.
I would look to the common maintenance items first, air filter, plugs wires, base timing and idle control. You my increase power by servicing these areas. The AC will still draw out gobs of power but, that's a Miata. Does it still have the original exhaust system? Corrosion or age can cause restriction within which can rob you of power output.
If your primary issue is just at idle then you may have experienced a ICS (idle control solenoid) failure. It is the device that recovers and holds the idle when the ancillary items come on line. In other words when the AC, PS or Alternator are switched on the ICS increases the idle speed to compensate for the load. If the car seems to fall on its face when the AC comes on at idle then this is likely at fault. The idle should flutter but maintain RPM not drop when the device is working properly.
