A/C Condenser Fans Always On - Bypassed Pressure Switch Ground Wire

Electricalintermediate✓ OP Confirmed

Problem

A/C condenser fans (all 3 on a 1990 7MGTE AT) run constantly whenever the ignition key is turned on, even though the A/C system is not functional and has no refrigerant.

All 3 condenser fans run as soon as key is turned to ON positionFans never shut off while car is runningA/C system non-functional with no refrigerantA/C high pressure switch and dual pressure switch wiring cut and disconnected

Root Cause

A previous mechanic had bypassed the A/C high pressure switch by forcibly grounding the fan relay control wire (blue with white stripe, L-W) to the fuse box mounting bolt. This was done because the A/C pressure switches were disconnected and cut, so the fans would never activate normally. With the relay coil ground permanently connected, the fan relays energized as soon as the ignition provided 12V+ to the relay coils, running all 3 fans constantly.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted November 2025 on SupraForums.com