Difficulty

Moderate

Steps

3

Time Required

                          45 minutes

Sections

1

  • Freezer Relay
  • 3 steps

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Introduction

The second coil is controlled by a starter relay. It works with a thermistor - a resistor whose resistance increases once it reaches a certain temperature, thereby cutting current to the starting coil.

If the starting coil burns out, you might notice your freezer not getting cold while compressor gets warm. Often the thermistor will shatter, and you can hear it rattling around in the relay, but not always. You can check the relay with an ohmmeter. The BQP2-4.7 should read about 4.7 ohms at room temperature. Any other reading means it’s probably failed.

For whatever reason, it’s relatively impossible to get your hands on a BQP2-4.7, so we’re going to repair one using parts from an easy to find and inexpensive similar relay - the QP2-4R7.

What you need

Step 1

              Inspect your relay
  • The burnt out relay. Notice the brown heat marks. This picture is with the insides already removed, so yours will show leads.

The burnt out relay. Notice the brown heat marks. This picture is with the insides already removed, so yours will show leads.

1024

Step 2

              Disassemble the QP2-4R7 and BQP2-4.7
  • Pry the bottom off the QP2-4R7. You may break the tabs on the bottom plate, but that’s OK since we don’t need the housing. Look inside and you’ll see the disc held in by a short metal brace. Use pliers to remove the brace and remove the disc.
  • Repeat the process for the BQP2-4.7, but be careful not to damage the housing if you can.

Pry the bottom off the QP2-4R7. You may break the tabs on the bottom plate, but that’s OK since we don’t need the housing. Look inside and you’ll see the disc held in by a short metal brace. Use pliers to remove the brace and remove the disc.

Repeat the process for the BQP2-4.7, but be careful not to damage the housing if you can.

Step 3

              Inspect the parts
  • Notice the burnt out component in the red box vs. the shiny new one in the green box.
  • Clean the leads on the BQP2-4.7 of any residue to ensure a good connection to the new thermistor disc.
  • Reassemble the BQP2-4.7 by first inserting the leads, then pushing the disc between the connectors, and finally snapping the cover plate back on.
  • If you have an ohmmeter, check that you read about 4.7 ohms across the leads at room temperature.

Notice the burnt out component in the red box vs. the shiny new one in the green box.

Clean the leads on the BQP2-4.7 of any residue to ensure a good connection to the new thermistor disc.

Reassemble the BQP2-4.7 by first inserting the leads, then pushing the disc between the connectors, and finally snapping the cover plate back on.

If you have an ohmmeter, check that you read about 4.7 ohms across the leads at room temperature.

Put the relay back into your freezer and test it out.

Be aware that the freezer will only turn on if the disc is cool, so if it turns on at first and you turn the freezer off, it probably won’t immediately turn on again because the thermistor is already warm. Give it 5 minutes and try again.

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                                                                                      6 other people completed this guide.

Author

                                      with 1 other contributor 


                    Perry Tancredi

Member since: 11/29/2012

281 Reputation

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MAZANDU mazandu - Mar 2, 2018

Reply

Good instructions; I tried doing this and was helpful. I found the actual part; it’s now available on amazon. [|Check here:] https://www.amazon.com/gp/offer-listing/…

Perry Tancredi - Nov 29, 2018

Thanks! I’m glad this has helped some folks and I’m glad you got the part. I just checked that link and they’re no longer available. When I found them, they were five times as expensive as the other relay, but in the end the money might be worth it. I happened to have the other part, so thought I’d try the rebuild.

rdrey1 - Apr 4, 2019

Reply

How long should a working disk take before it clicks off? Mine seems to get too hot after 10-20 seconds, but I see nothing obviously burnt.

Perry Tancredi - Apr 30, 2019

Hi - it should only take a few seconds. 10-20 seconds sounds like too much, like it’s not stepping down for some reason.

stevebevan232 - Apr 27, 2019

Reply

I have a JPQii 4.7 two pin relay and cannot find a replacement. The one I have is new but reads 0 ohms