The RD Holder HVAC Pro is to help a AC technician service an Air Conditioning system. Troubleshooting of an air conditioning system is a step by step procedure. I have found that a 4 step procedure is the best way to see how well a system is operating. The 4 steps are: 1. Volts and Amps, 2. Evaporator Superheat, 3. Condensing Subcooling and 4. Temperature difference of coils. Not one of these method alone can be used by itself to charge or troubleshoot an air conditioning system rather they must be used together to ensure efficiency and capacity.

Not only is voltage very critical but the amp can tell us how hard a compressor is working and is a good indication of a charge

Evaporator superheat is a calculation of the amount of liquid refrigerant going into the evaporator and the heat load of an air conditioner evaporator.

Subcooling is the amount of liquid held back in the condenser. This allows the liquid to give up more heat, below saturated pressure- temperature.

Temperature difference of an evaporator coil will vary with the total heat of the air entering the evaporator and the load on the condenser. This temperature will vary from 10º F to 30º F depending on total heat of the air entering the evaporator.

When you download HVACPro you will get both the phone version and the pad version. The first 5 diagrams are the phone version the last 4 are for the pad version.

What’s New

Version 1.2.7

Fixed pressure temperatures not updating for R-11, R-123, R-134a, R407c, R-410a, and R438a refrigerants

Ratings and Reviews

5.0 out of 5
2 Ratings

2 Ratings

Drew10100 ,

Fantastic App!

I know this app is more than many HVAC/superheat apps, but it is well worth the money! The developers also included M099 refrigerant as one of the many refrigerants available. They also update the app pretty frequently unlike many of the other HVAC apps available in the App Store. If you are an HVAC tech, get this app!!!

Schon1963 ,

Where is 404A

Need to add 404A to refrigerants,thanks!

Hvactech117 ,

9 of 10

Verified accuracy of this app. The only training problem it did not analyze correctly was a non-condensables problem. Overall this app is well made, easy to use and a useful tool.


Roger Holder
40.2 MB

Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.


English, Czech, Danish, Dutch, Finnish, French, German, Greek, Hebrew, Indonesian, Italian, Japanese, Korean, Malay, Norwegian Bokmål, Polish, Portuguese, Russian, Simplified Chinese, Spanish, Swedish, Thai, Traditional Chinese, Turkish, Vietnamese

Age Rating
Rated 4+
© R D Holder Eng


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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