Johnson Controls P29NC-38 Pressure Control

The Johnson Controls P29NC-38 is a heavy-duty low pressure cutout control designed to protect commercial refrigeration and HVAC systems from low suction pressure and lube oil failure. Engineered with a built-in 120-second time delay, this control prevents nuisance shutdowns caused by momentary pressure fluctuations during startup or normal cycling. This model is the official P29NC-38 direct replacement for legacy units including the P29NC-38C and P29NC-22, ensuring seamless mechanical and electrical compatibility for field service technicians.

Featuring a trip-free manual reset, the P29NC-38 requires technician intervention following a lockout, ensuring the high-side or oil system is inspected before operation resumes. The 36-inch capillary with a 1/4-inch flare nut allows for flexible mounting, while the ambient compensation provides consistent timing accuracy regardless of mechanical room temperature variations. This SPST pressure switch supports 120/240 VAC pilot duty applications and features a visible scale for precise cutout pressure adjustment from 20" Hg to 100 PSIG.

• Universal Compatibility: Serves as the drop-in HVAC pressure control replacement for discontinued P29NC-22 and P29NC-38C models.
• System Reliability: The 120-second delay relay distinguishes between temporary transient drops and genuine system failures to maximize uptime.
• Rugged Construction: Equipped with low-profile pressure elements capable of withstanding high overrun pressures during system leak testing.
• Field Serviceable: The timing mechanism and terminal board can be replaced in the field without removing the entire control from the refrigerant line.
• Accurate Monitoring: Simple single-pointer scale allows for rapid diagnostics and setup on the 20" Hg to 100 PSIG range.

Can I use the P29NC-38 for ammonia applications?
Standard P29 series controls are typically intended for non-corrosive fluorinated refrigerants. Always verify the connector style and internal bellows material before application in ammonia systems.

How do I wire this for 240V pilot duty?
The unit is rated for 120/240 VAC. Ensure the heater circuit is correctly jumped or wired according to the Johnson Controls wiring diagram located inside the cover to match your control circuit voltage.

Is this the correct replacement for a P29NC-22?
Yes, the P29NC-38 is the direct functional replacement for the P29NC-22, maintaining the same 120-second timing and manual reset logic.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.