Monthly Archives: July 2021

Home HVAC maintenance and trouble shooting

I am slowly accumulating information and knowledge about home HVAC system. Earlier on, I have a failure to start problem and it turns out to be a bad thermostat diagnosed by a friend.

General concept and knowledge about home HVAC system
This post provides basic knowledge about electricity.

Here are some possible items to document, 15 videos of maintenance tips

He suggests 15 maintenance tips to perform to maintain the system

1.	Uncover the unit
2.	Cleaning condensing coil
3.	Check wire and components
4.	Check the capacitor
5.	Check the suction line cover
6.	Level the base 
7.	Turn AC on earlier
8.	Check the fan – kick start
9.	Check the temperature drop
10.	--

	
  • Spray cleaning the unit thoroughly
  • Basic wiring diagram for HVAC system
    There are many online service tech resources, I have found a few very good tutorials

    The clean one is AC service tech llc on the home HVAC service board and wiring.
    This guy explains the wiring to HVAC very well, I want to give me a thumb up.
    And, he drew a very good diagram.
    Checking the power to the thermostat.
    Another guy makes an interesting little device to show the wiring diagram!
    He has an earlier video on this device, which explains the same concept.
    It turns out that he has a series of such device, this time it illustrates the "coil" function.
    Another post on a dummy digram also illustrates the connection and how they can fail. He lists out relevant books, more videos and tools to test the system and fix the problem.
    

    Google nest learning thermostat

    My friend has a failure, I need to understand the basic Google Nest Learning Thermostat
    It turns out that yoububer does a better job explaining it.
    

    Check the compressor

    Fan motor is not working, this guy provides a very general video but does not give very instructional step by step. I need to research more on it. 
    I like his post
    He puts out a very clear capacitor testing video as well. I think I still need a wiring diagram.
    Normally, there are two capacitors that power the outdoor condenser and condenser fan/motor like this 
    Someone says this way is not a good way
    Chris does not like the above video.
    
    Here is another hand drew diagramHanddrawingCapticitor
    

    Check the furnace

    All about capacitor fails
    I found this post extremely helpful.

    There are three major connections: labeled as C-connector, HERW, and fan. Like the follow figure shows.
    top connection.
    
    These three connection points can be identified by the number of tines, revealed by the following diagram
    
    
    
    4-tine common (black), 3-tines HERM (white) and 2-tines Fan (Green). In our system, there was one wire connected to the fan, two different color wires to the common, and two red wires to HERM. Referring to the following diagram.
    
    
    
    I found another post on how to wire these component with a duo capacitor. The wire is different from our system though, we have two wires go to HERM.
    
    
    

    Rattling Engine Noises from 2003 Acura MDX and Honda Odyssey compressor coil replacement

    My friend gets a 2003 Acura MDX, and recently he hears noises coming from the driving belt, we suspect it is the problem with the driving belt and I think it could be tensioner pulley

    Here is the driving belt diagram:

    Knowledge preparation from a good source

    My friend like Eric’s video, which is also a good resource for auto repair.

    As the above diagram shows, a serpentine belt slithers over several pulleys whose rotational energy powers different devices. The belt is typically connected to the following accessories:

    Alternator
    The belt helps power the alternator, which keeps your battery charged.
    
    Power Steering Pump
    The power steering pump pressurizes the hydraulic steering fluid. Without the belt running the pump, the driver could experience a sudden loss of power steering, which makes handling much tougher.
    
    Air Conditioning Compressor
    An air conditioning compressor sends fluid throughout the air conditioning system, so its functionality is key to keeping cool.
    
    Water Pump
    An engine needs the water pump to push coolant through the system and keep its temperature down. If the belt fails, it could result in your car overheating.
    
    Water pump is driven by the timing belt that is connected to the driving shelf.
    
    There is a video of replacing the timing belt, it shows the details belt/pulley connection.
    
    

    I have found the closest video is from the second generation MDX. It is good enough for me to start from somewhere.

    The lower 12 mm bolt: 22 newton-meter, 16 lb/ft
    The 14 on the tensioner: 44 newton-meter, 32 lb/ft
    The pulley only torque is: 59 lb/ft
    

    Step by step protocol

     	
  • Prepare and line up the tools
  • Sketch the belt diagram
  • Loosen the tensioner and release the belt
  • Remove the 14 mm bolt and 12 mm bolt to remove the tensioner
  • Install the new tensioner: 16 lb/ft for the 12 mm bolt and 32 lb/ft for the 14 mm bolt
  • Install the new belt to wrap all the component, by loosing the tensioner to finish
  • Unfortunately, replacing the belt and tensioner does NOT solve the problem. From Scotty’s video, he explains that it could be other pulleys. Well, we have water pump or alternator etc. He has another video that further explain how to use the right tool for the right job.

    Another guy has summarized eight different kinds of noises. We will see how we can get to the bottom of it.

    I have to study more and I am accumulating more videos at this point and after further examination, it starts to points to the crankshaft or harmonic balancer.

     	
  • This is the first video
  • Okay, after all these "research", I think I eventually find a guy that shows exactly the the problem of harmonic balancer and how to fix it. I think this is a good video for fixing balancer wobbling.
  • This video explains very well on what can go wrong if the harmonic balancer goes bad.
  • Someone posted replacing the timing belt that needs to remove harmonic balancer as a start.
  • The same guy posted the installation video as well.
  • To clarify, the crankshaft pulley is different from the harmonic balancer.
  • To get the job done, we would need a crank pulley tool and a puller
  • After all these effort, I come to this diagnosis. The wobbling noise comes from the AC clutch pulley. here are some good videos fixing the clutch.

    I noticed the wobble when I wiggle the wheel bearing, so, I think it could be it. I found a very good video, and hopefully we can fix it somehow. 
    
    This guy shows a good video tutorial.
    
    Another guy is doing the same in vitro video.
    
    This one is for 2003 MDX specifically.
    
    There could be challenges removing the plat or the pulley, spacer is also critical for the AC to work.
    
    This guy explains in more details on how to get the plat off and measure the space between the plat and the pulley.
    
    The guys shows the important to check gap between the plate and clutch pulley.
    

    To replace the clutch pulley seems quite simple and intuitive, but I encountered resistant from step 1. The following are the steps I need to achieve one by one

    	
  • Remove the 10 mm bolt on the clutch plate. Luckily, done
  • Remove the clutch plate, but I can't!

  • Can I use these tools to remove it?
  • Remove the clutch pulley, by removing the clip ring, then hammering it out.
  • Mount the clutch pulley back
  • Mount the clutch plate
  • Adjust the gap between the plat and clutch pulley
  • Going through all these research, I want to document something related to the car AC system.

    This video demonstrates how to diagnose a bad compressor.
    

    Parts and tools for this project

    Here is the serpentine belt assembly kit that I have replaced and it does not help to solve the problem.
    
    Here is the compressor that fits 2003-2006 Acura MDX
    
    Here is the compressor clutch and pulley that fits 2003-2006 Acura MDX
    

    Okay, it seems that we may have to be prepared to replace the compressor!

    Main steps are here as shown in the video:

    	
  • Remove the serpentine belt
  • Remove the coolant fans to get room
  • Discharge all the freon
  • Disconnect the high/low pressor connection
  • Remove top two bolts from the top, two bolts from the bottom
  • Unplug the connection socket
  • Remove the metal bar to get more room
  • Remove the old ac compressor
  • Reverse the above steps and make sure all the connection are secured, reinstall the belt
  • Be sure to use the new o-rings for pipe connections.
  • Re-charge the freon
  • To work with the pressor, here is a good video on this.

    2007 Honda Odyssey

    Another friend has a car AC issue, his car is Honda Odyssey 2007 and we diagnose that the problem could be the “coil” failure

    He found a video, but I feel that the person did not record those difficult steps.
    So, I searched around and found another video, he did not record the whole process, but at least he mentioned a few challenge steps:
    
    
      He mentioned that the location of the compressor makes it hard to reach
      The first trick is his wife helped to remove the serpentine belt from the top.
      He mentioned the tool to hold the cap when he tried to loosen the 10 mm center bolt.
      He show two different ring snap plier, they are very hard to be removed.
      He mentioned to using a rubber mallet to snap the pulley off
    These are difficult steps he encountered, we can see more but hopefully less.