1981-1983 Plymouth PB150 A/C Compressor Cut-Off Switch Replacement Guide
If your PB150's air conditioning has stopped working, a faulty A/C cut-off switch is a common and inexpensive part to check.
- The A/C Cut-Off Switch on the PB150 is a low-pressure safety switch located on the accumulator.
- A bad switch will usually cause the A/C compressor to not turn on at all.
- Aftermarket brands like Four Seasons and Global Parts are your only realistic options, as new OEM parts are unavailable.
- You may need a professional to evacuate the A/C system before you can safely and legally replace the switch.
Is Your PB150's A/C Suddenly Blowing Warm?
When the air conditioning in your classic Plymouth van quits, the problem can seem complex. However, before assuming a major failure like the compressor itself, it's wise to inspect the A/C compressor cut-off switch. On these vans, it's a low-pressure cutout switch, meaning its primary job is to protect the compressor if refrigerant leaks out. A failure of this small switch will prevent the compressor from turning on at all, resulting in warm air from the vents.
Symptoms of a Failing A/C Cut-Off Switch
A bad cut-off switch on your PB150 will show clear symptoms. Because this vehicle predates modern computer diagnostics, you will not get a check engine light or a trouble code for this failure.
- A/C Compressor Does Not Turn On: The most common symptom. You'll turn on the A/C, but you won't hear the distinct 'click' of the compressor clutch engaging. A broken switch cannot send the signal to power the compressor.
- A/C Blows Only Warm Air: With the compressor disengaged, the refrigerant cannot circulate to cool the air. The system will only blow ambient-temperature air through the vents.
- Intermittent Cooling: In some cases, a failing switch might work sporadically, causing the A/C to cut in and out unpredictably.
Choosing the Right Aftermarket Switch
For a vehicle from the early 1980s, new Original Equipment (OEM) parts from Mopar are generally no longer available. The replacement market consists entirely of aftermarket brands. For the 1981-1983 PB150, brands like Four Seasons and Global Parts Distributors (GPD) are the common choices.
| Brand Tier | Brands | Quality & Cost Assessment |
|---|---|---|
| Standard Aftermarket | Four Seasons, Global Parts (GPD) | These brands provide functional, budget-friendly replacements. Forum discussions show mixed real-world results for A/C components from these brands, with some owners reporting long life and others experiencing early failures. Given the age of the PB150, these are the most practical and available options. Quality is generally considered adequate for keeping a classic vehicle's A/C operational. |
| New OEM | Mopar | No longer available new for this specific part and vehicle. |
Refrigerant Evacuation May Be Required
This switch is located on the A/C accumulator. On some vehicles, there is a Schrader valve (like a tire valve) in the port, which allows you to replace the switch without losing refrigerant. However, many older systems do not have this valve. If you unscrew the switch and refrigerant begins to escape, the entire system must be professionally and legally evacuated before you can proceed. Releasing refrigerant into the atmosphere is illegal and harmful. If you are unsure, assume the system needs to be evacuated by a certified A/C technician.
Frequently Asked Questions (FAQ)
Can I replace the A/C cut-off switch myself?
Yes, the physical replacement is simple. It involves unplugging the electrical connector and unscrewing the switch. However, as noted above, you may need a professional to evacuate the A/C system first, which makes it a less straightforward DIY job. If your van has a Schrader valve under the switch, it's a very easy 10-minute fix.
My van was converted from R-12 to R-134a refrigerant. Does that matter?
The switch itself is not affected by the type of refrigerant. Its function is to react to pressure, which is similar for both R-12 and properly converted R-134a systems. Aftermarket switches from brands like Four Seasons and GPD are designed to work with modern systems and conversions.
Are there any recalls for the 1981-1983 Plymouth PB150 A/C system?
No. Searches of the National Highway Traffic Safety Administration (NHTSA) database show no recalls or technical service bulletins (TSBs) related to the A/C system or its components for this vehicle. Any failures are due to the age and wear of the parts.
Should I replace other parts at the same time?
If the A/C system must be opened and evacuated to replace the switch, it is an excellent time to also replace the A/C accumulator/receiver-drier. This component contains a desiccant that absorbs moisture, and its lifespan is limited, especially once the system is exposed to air. Replacing it is a best practice during any major A/C service.
Technical Specifications
Mounting Location: Accumulator/Receiver-Drier. Type: Low-Pressure Cut-Out Switch. Connector: 2-Prong Electrical Connector.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Plymouth PB150: