Tag: HVAC Tech Tips

Diagnosis and Troubleshooting A/C Systems

Posted on April 6, 2021 - 1News, Air Conditioning 101

Proper A/C system performance is achieved with many components working together to provide cab comfort for the driver and passengers. The item that receives the most attention is the Compressor. The compressor operates as the “pump” of the system, keeping the refrigerant circulating and increasing the refrigerant’s pressure.

All compressors have two sides: Suction and Discharge. The refrigerant is drawn into the compressor’s suction side as a cold-low pressure vapor and then is compressed, thus raising the refrigerant pressure and temperature. The high pressure-high temperature vapor refrigerant is then pumped out of the compressor’s discharge side to the condenser.
As the compressor moves the refrigerant through the system, the refrigerant oil also moves with the refrigerant.

AC System - Replacement HVAC Parts & Supplies - ATC I 1-800-295-4156


Why are compressors removed?

1) Loss of a refrigerant charge – Cold refrigerant entering the compressor on the suction side coming from the evaporator provides cooling to the compressor. With a loss of refrigerant, the compressor overheats. Also, with a loss of refrigerant, the oil is not returned back into the compressor and eventually the compressor will run dry. AC Compressors - Replacement HVAC Parts & Supplies - ATC 1-800-295-4156

2) Contamination – Particles found inside the system will cause internal damage to your system. These particles can cause blockage at the condenser, expansion valve or damage to the internal parts of your compressor. Contamination must be removed from the system by using the correct flushing procedures.

3) Misdiagnosis – Change the wrong part is a common procedure in repair A/C failures. The system must be properly diagnosed before changing parts and pieces.

What are the most common causes of compressor failures?

1) Low Refrigerant Charge AC Compressors - Replacement HVAC Parts & Supplies - ATC 1-800-295-4156
2) Leaks with the System
3) Contamination in the System
4) Lack of Lubrication
5) Clutch Failure due to System Failure
6) Blockage or Restriction within the system
7) Insufficient Condenser Cooling

What happens if a compressor continues to run under a low refrigerant charge?

1) Overheating of the compressor occurs. AC Compressor - HVAC Replacement parts & Supplies - ATC I 1-800-295-4156
2) Refrigerant oil circulation slows down and returns very little back to the compressor
3) Without proper lubricant and refrigerant charge, the compressor will “lock-up” and destroy the compressor.
4) The critical low charge point is reached when the system has 50% or less of the recommended refrigerant charge.
5) Disabled or Malfunctioning switches that allow the compressor to run in a low charge situation.

With mechanical reliability at all-time highs, heavy-duty A/C components rarely fail. In fact, components mainly fail because of the contaminated refrigerant oil and general lack of preventive maintenance. Proper maintenance increases operating time and saves money by identifying concerns before they become problems.

More Pre Season maintenance tips

A/C Preventative Maintenance
A/C Systems – How a simple inspection can save, 
How To Inspect an A/C Compressor
A/C Compressor Check Up
How To Troubleshoot your A/C Electrical system

Best selling mobile HVAC parts by Make. 


Completing the A/C Best Practices on our Youtube channel ATCTV, we feature
Basic Troubleshooting, 
How To and Which Components to Inspect
Examining Compressor Failures
Thermistor Kit for Navistar

Arctic Traveler Canada is always focused on the application of Air-Conditioning, Heating, Pressurization and Refrigeration of cabins and cargo areas of mobile vehicles, both on-road and off-road. As a Master Stocking Distributor, ATC offers Air Conditioning systems and replacement parts for any heavy duty vehicle. Call 1-800-295-4156 or visit www.atc.ca for more information.

A/C Compressor Check

Posted on August 1, 2019 - 1News, Air Conditioning 101, Technical Tips

Wondering why your system has a low refrigerant charge?
It could be because of a leak that needs repair, or a high-side blockage that limits refrigerant flow to the compressor. Diagnose those problems first, and if not resolved, perform this simple 4 step A/C compressor function check, before you remove the compressor from a vehicle. 

Service Tip: Remember when you open the A/C system, you should change your filter drier to remove contaminants and minimize damaging moisture in the system.
AC Compressor - The heart of your air conditioning system.
4 step tech tip
1. Is the compressor rotation smooth? With the vehicle off, turn the compressor shaft with a 14-mm socket. If you feel grinding or hanging as you rotate the shaft, there may be broken components within the compressor. If the rotation is smooth, move on to Step 2.
 
2. Is the coil getting more than 11.5 volts? Take a reading with the engine running and the clutch engaged. If there’s insufficient voltage, get to work on that. Otherwise, move on to Step 3.
 
3. Is the coil resistance between 2.8 and 4.4 ohms for a 12 vdc system and 11.2 to 17.6 ohms for a 24 vdc system? Any resistance outside these ranges will prevent the clutch from engaging or will cause used circuits to open. If the resistance measures correctly, continue to Step 4.
 
4. Is the compressor able to produce 350 psig or more? The compressor should be able to build over 350 psig on the high side with the condenser airflow restricted, and also able to pull the suction side down to 5 psig when the TXV is closed. If needed, the technician can close the TXV by chilling the charge head using a can of dust-off held upside-down.This will temporarily freeze the TVV charge head and cause it to close. If the compressor is operating correctly, the suction pressure will drop below 5 psig.

Need more info. Go to our blog, ATCNEWS or view more tips on the links below
Arctic Traveler Canada has a complete line of replacement parts & HVAC systems for all makes, any HVAC Part or System. Call us today for more information .  

How to inspect an A/C Compressor

Posted on May 26, 2016 - 1News, Air Conditioning 101, Technical Tips

Take these steps to inspect an A/C compressor to ensure it really needs replacing before you pull it from a heavy-duty vehicle:

1. Is The Compressor Rotation Smooth?
With the vehicle off, turn the compressor shaft with a 14-mm socket. If you feel grinding or hanging as you rotate the shaft, it’s probably due to broken components within the compressor. If the rotation is smooth, move on to Step 2.

2. Is The Coil Getting More Than 11.5 Volts?
Take a reading with the engine running and the clutch engaged. If there’s insufficient voltage, get to work on that. Otherwise, move on to Step 3.

3. Is The Coil Resistance Between 2.8 And 4.4 Ohms?
Any resistance outside this range will prevent the clutch from engaging or will cause used circuits to open. If the answer is yes, continue to Step 4.

4. Is The Compressor Able To Produce 350 Psig Or More?
If not, leave the compressor where it is. The system may have a low refrigerant charge because of a leak that needs repair, or a high-side blockage that limits refrigerant flow to the compressor.

Tech Tips from Red Dot
” We see lots of compressors that are returned fully functional and therefore not warrantable.
Get the diagnosis right. Inspect an A/C compressor before you pull the component from the vehicle.”


For expert insight into common failures and causes, watch Examining Compressor Failures on ATCTV
While there, check out How To and Which Components to Inspect and Basic A/C Troubleshooting to further your understanding of A/C Systems.

For more information about AC Compressors or any HVAC component, call the mobile HVAC specialist Arctic Traveler Canada at 800-295-4156.

How to troubleshoot your A/C Electrical system

Posted on May 26, 2016 - 1News, Air Conditioning 101, Technical Tips

Tech Tips from Red Dot

On any vehicle and virtually any A/C system, electrical problems are among the hardest to troubleshoot. If you suspect an electrical problem with the A/C system, here’s a two-stage inspection routine that virtually anyone can do with no special tools or skills:

1. Inspect Electrical Connections

As you perform a visual inspection under the hood (cab) and/or at the rooftop condenser, take a moment to check all electrical connections both visually and by feel. Make sure all leads and wires are properly supported and securely connected, and that there’s no corrosion or grime on the leads or connectors.

2. Check Electrical Current Flow and Device Functions

Perform the following steps to check the current flow and electrical device functions:

  • Turn on the ignition. 
  • Turn on the A/C system. This will power the thermostat and clutch. If it does not come on, use the A/C mode switch to check the leads to the switch. You should hear a “click” from the thermostat and hear the clutch drive plate “snap” against the clutch pulley. 
  • Check fuses. If all the connections are clean and tight and there’s still a failure, check the fuses in-cab as well as in-line.
  • Check A/C clutch engagement. Since you can’t see and may not hear the clutch engage, get out and look at the clutch. If it’s engaged, you will see that the drive plate is against the pulley and not slightly spaced from it. If you aren’t sure the clutch is engaged, look for the lead wire connector near the clutch. Break and close that connection. The clutch will disengage and engage again.
  • Test blower speed operation. Some systems have a common switch that turns on the air conditioner and powers the blower motor. Test blower speed operation by adjusting this or the separate blower control switch. Feeling the air flow from the ducts or note blower sound (speed) changes.
  • Inspect roof-mounted condensers. Don’t forget to inspect roof-mounted condensers and A/C units for dirt and debris. Be sure the condenser fan(s) are working properly and all parts and electrical connections are securely fastened. The roof-mounted condenser fans may come on when the system is turned on. Like the thermostat and most clutches, the normal on-off cycling action cannot be observed until the engine is running with the A/C system on.
Once your visual inspection is complete, talk to a qualified A/C technician about what you found. Your troubleshooting efforts will be rewarded with a speedier repair and perhaps a lower repair bill.

Quick Heater Service Tip from Reddot
  • When the status is “heater fan doesn’t work,” check the ground connection for rust, paint, grime, or some other obstruction at the terminus.
  • If the motor doesn’t have a ground wire, its mount serves as a ground connection. Make sure nothing impedes the mount’s ground path.
  • Use a multimeter to make sure you’re getting full voltage to the motor. Once you know the voltage is adequate, you can then look for worn brushes, dirty squirrel-cage fans, damaged fan blades, and other more typical motor problems.

Arctic Traveler Canada is an MSD/Master Stocking Distributor and Authorized Technical representative for many industry-leading products. Call us today at 1-800-295-4156 to see what 55 years of excellence can do to achieve your business objectives.