Hack-free HVAC
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HVAC technician with hobbies including DIY electronics, solar, automotive, & outside-the-box projects
VAI resort & Mattel theme park update - June 11th, 2026
My daughter and I took a trip over to the VAI and Mattel location to see the progress on the construction.
Not too much to really notice, unfortunately.
07/11/2026
Testing motor LRA to RLA transistions on a oscilloscope 👍
Using a single phase fan motor to demonstrate the Locked Rotor Amps a motor pulls when it is energized that then transitions down to the Run Load Amps once the motor is up to speed. I test this with a variety of run caps and with a start cap applied as well.
00:00 Intro to the experiment
00:51 Test start with 5MF run cap
02:08 Test start with 10MF run cap
03:26 Test start 5MF and start cap
04:55 Why run caps do not need discharge
05:19 Adding more start caps
07:11 Outro
I had to be ⚡️MacGyver⚡️ to save the July 4th vacation trip! 💪👍
DIY soft starts revisited - Part 3 - Testing variable speeds via half wave skipping on a condenser fan motor.
See full video here --
https://youtu.be/FxS_YWKd624
06/29/2026
DIY soft starts revisited - Part 3 - Testing on a condenser fan motor.
This week I finally got around to building a circuit to test the speed shifting theory with some high voltage to a condenser fan motor.
00:00 Intro
00:12 I seemed to have made a mistake
05:27 Creating the first triac board
06:45 Making another triac board
11:06 Testing with high voltage applied
12:04 Testing the motor on 240VAC
28:32 Manually switching a start cap
31:45 Maybe I should do some more tests
35:47 Outro
06/25/2026
Soft starts revisited - Part 2 - Testing SCRs and TRIAC frequency skipping.
In this video I use a microprocessor to detect the zero cross of the negative to positive 60Hz sine wave to determine when to energize the gate of a pair of SCR's to be able to skip sine wave half periods to create a pseudo lower frequency output.
00:00 Intro
00:40 Calculatinig cycle periods to skip
02:22 Viewing new frequencies on the scope
03:57 Stepping up to high voltage for test
09:19 Abandoning twin SCRs for single triac
09:44 Single tria test circuit
11:44 Outro
06/25/2026
Diagnosing a 30RAP Chiller for compressor trips - Noisy ODM - Using Device Manager software
Soft starts revisited - Pondering some weird control ideas
Me nerding out on some ideas for some simple circuit motor speed controls
00:00 Intro - Soft starts revisited
02:00 The original EasyStart
05:42 Zero cross detection
07:35 Controlling the gate timing of the SCR
09:39 Asking AI to troubleshoot
13:28 Pondering skipping sine wave half cycles
15:05 Trying to get AI to create a spreadsheet
The facility really needed this Rooftop unit to be working.
This is the procedure I will perform to try to get a failed TXV to function again until it can be replaced.
1) If the sensing bulb wasn't obviously broken, I will first start by cutting the equalizer line to confirm that it is not plugged (refrigerant will spray out from the tube welded into the suction pipe).
Then, I pinch off and weld shut the tube soldered into the suction pipe and then extend the TXV equalizer tube to a piece of 1/4" copper that I will flare and connect to the suction service valve with a swivel tee.
2) If that is not the remedy, I will cut the capillary tube near the TXV sensing bulb (this one broke as I handled it). The charge should be released if it did not leak out. Then I will pull out the old tube and reconnect the TXV Dome capillary tube and add a schrader stem to add a charge.
This will not be perfect, however, it should push overcome the spring and open the needle valve in the TXV.
In this example, the suction was a bit low and superheat a bit high, however it was close enough to keep the system, online a few days and it even had a decent temp split 👍
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