Mechanics

ROUGH IDLE & POWER LOSS WITH A/C ON

Mazda 626

Make & Model: Mazada 626 LX 1998; 4 cylinder 2 liter
Mileage: 96,000

Background info: I've had the timing belt replaced, I've replaced the IAC, vacuum hoses, new plugs & plug wires, cleaned EGR valve, had alternator tested - it tested good, replaced a/c & heater control unit. Local mechincal adjusted base idle.

The problem starts when anything puts a load on the motor - the a/c is the greatest drain. The RPM's dropped drastically when a/c is turned on. When alternator was tested I did notice a 19 amp drain on the charging system when the a/c was cut on. It went from 69 to 50 amps. Is this normal? I've pulled out the relay for the compressor and it still pulls down the motor with the a/c on. I've taken the compressor belt off and it still does it. I've jumped out the high and low pressure switches on the a/c system and it still does it. I've looked for a short in the wiring and can't find one. I don't have any check engine lights or codes. If my PCM is failing shouldn't I get a code? I have not had the a/c system checked yet. Any help would be GREATLY appreciated.
Avatar
Davis63
June 9, 2007.



So with the a/c relay out of the car, it still draws down when turned on? I take it the comp isnt engaging? It wont if you have the correct relay. Be sure of this and get back to me. Otherwise you have some strange electrical things going on

Tiny
Jack42
Jun 10, 2007.
Yes. Correct the comp isn't engaging. I'm sure I have the right relay. I've even unplugged the comp clutch. And I've removed the a/c belt off the clutch, ran the car, turned on the a/c it still pulls down.

Tiny
Davis63
Jun 10, 2007.
Are you turning on the blower fan or just the A/C?

Tiny
Jack42
Jun 11, 2007.
The a/c will not come on unless the blower fan switch is in position (1). There are five switch positions. (0-4) 0 positon is off and 4 is high. I have disconnected the blowers main plug, which completely takes the blower out of the system and when I turn the a/c on it still pulls the motor down. I think the blower is OK.

Tiny
Davis63
Jun 11, 2007.
Sounds like it is time to tear into it and see why it pulls the engine down when nothing is on. Go to link at bottom of main forum page for repair manuals, will have all wiring diagrams so you can see what you are doing

Tiny
Jack42
Jun 11, 2007.
I Have the Haynes Repair Manual for my car. I been through the heating and air conditioning system wiring diagram and I did find one thing. If I pull out the 10 amp a/c fuse the problem goes away but, this also disables the controls for the a/c. The a/c fuse supplies power to the air intake actuator (part of the blower unit), swing louver (oscillating vents in middle of dash) and to the heater/ a/c control unit. (Which I have already replaced) I have also unplugged the louvers and the blower unit and the proble is still there. I wish I had a diagram of the control unit so I could see where the power from the a/c fuse go after the a/c switch is in the on position. Do you know of a place I can get this electrial diagram? Its not in the Haynes Manual.

Tiny
Davis63
Jun 11, 2007.
Try the link I told you. That is professional software, not the book you buy at Autozone

Tiny
Jack42
Jun 12, 2007.