Chevrolet Blazer A/C Compressor Cut-Off Switch Guide (1987-1999)
If your Blazer's A/C isn't blowing cold, a faulty pressure switch could be the simple fix you need.
- A non-working A/C is often caused by a bad low-pressure switch, not a bad compressor.
- You can test the low-pressure switch with a paperclip to see if the compressor engages.
- Replacing the low-pressure switch on the accumulator is a simple DIY job that doesn't require discharging the system.
- Replacing the high-pressure switch on the compressor requires a professional and a system recharge.
Is a Bad A/C Switch Why Your Blazer's Air is Warm?
When the A/C in your 1987-1999 Blazer stops working, the problem is often electrical, not a major component failure. The A/C cut-off switches are common failure points that can prevent your compressor from turning on. The most frequent symptom is the A/C compressor clutch not engaging at all when you turn on the air conditioning. You'll hear the fan blowing, but the air will never get cold. Another sign can be the compressor clutch turning on and off very quickly, which is called short cycling. In some cases, particularly on models with automatic climate controls, the A/C light on the dashboard might blink a few times and then turn off.
Quick Diagnostic Trick
You can perform a simple test on the low-pressure switch. Locate the switch on the A/C accumulator (a large aluminum can near the passenger side firewall). Unplug its electrical connector and use a small wire or paperclip to connect the two terminals inside the plug. If the A/C compressor clutch engages, you've confirmed the problem is either a bad low-pressure switch or the system is simply out of refrigerant. Do not leave the jumper wire in place for more than a few seconds, as this bypasses an important safety feature.
Choosing the Right Aftermarket A/C Switch
Before buying a part, you must identify which switch has failed. There are two different switches, and they are not interchangeable.
- Low-Pressure Cycling Switch: This is the most common switch to fail. It is located on the accumulator/drier and simply screws onto a Schrader valve. This means you can replace it yourself without losing refrigerant.
- High-Pressure Cutout Switch: This switch is located on the back of the A/C compressor. Replacing this switch requires a professional to safely evacuate the refrigerant from the system first. It is often held in place with a snap ring.
For a vehicle of this age, aftermarket brands like Four Seasons and Global Parts (GPD) offer a cost-effective solution. Online forums show mixed reviews for many aftermarket A/C parts, with some users reporting early failures with various brands. However, for a simple part like a pressure switch, both Four Seasons and GPD are considered standard, acceptable quality replacements that are widely available. Given the low cost of the part, choosing a readily available aftermarket option is a practical choice for most Blazer owners.
Cost to Replace a Blazer A/C Cut-Off Switch
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Switch | $22.39 - $54.11 |
| New OEM (ACDelco) Switch | $45 - $75 |
| Shop Labor (Low-Pressure Switch) | $50 - $100 |
| Shop Labor (High-Pressure Switch) | $120 - $250+ (includes system evacuation/recharge) |
Frequently Asked Questions
Can I replace the A/C switch myself?
Yes, if it's the low-pressure switch on the accumulator. It unscrews from a valve, so you won't lose refrigerant. However, the high-pressure switch on the compressor requires special equipment to evacuate the A/C system, and that job should be left to a professional.
My A/C light blinks. Is it the switch?
It could be. On Blazers with automatic climate control, a blinking light indicates the system has detected a fault. This could be caused by a bad pressure switch, low refrigerant, or another issue in the system. The best approach is to check the refrigerant pressure first, then test the low-pressure switch.
What's the difference between the high-pressure and low-pressure switch?
The low-pressure switch protects the compressor from running with too little refrigerant. The high-pressure switch protects the whole system from bursting due to excessive pressure. They are located in different places and are not interchangeable.
Are there any recalls for the A/C switch on my Blazer?
No, searches of the National Highway Traffic Safety Administration (NHTSA) database did not find any recalls or technical service bulletins (TSBs) related to the A/C pressure switches for the 1987-1999 Chevrolet Blazer.
Technical Specifications
OEM Part Numbers: 15-5643 15-50812 22634172
The A/C system uses both a low-pressure cycling switch and a high-pressure cutout switch. The low-pressure switch is typically located on the accumulator and is threaded onto a Schrader valve. The high-pressure switch is typically located on the rear of the compressor and is sealed with an O-ring and held by a snap ring. Connectors are typically a 2-pin design.
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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.
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