Vintage Air Gen 5 SureFit HVAC Kit VS OEM Foxbody Mustang 5.0 HVAC
Trust the Science: OEM vs. Vintage Air HVAC in a Foxbody Mustang 5.0
In the name of science, I decided to run a real-world HVAC experiment comparing the Vintage Air Gen 5 87-93 Ford Foxbody Mustang 5.0 to a OEM Ford Fox body Mustang 5.0 HVAC system.
The test mules are a 1991 GT convertible with a Ford OEM, bone-stock heater and AC system. The other is a 1992 LX coupe equipped with a Vintage Air Gen 5 SureFit HVAC system. The goal is simple: find out which system blows harder and which one blows colder.
To keep things as fair and as scientific as possible, I will be using a wind speed and temperature measuring device. Both cars will be tested in controlled environments - my home garage where the inside temperature is set to 72 degrees Fahrenheit. I will also give each car a 60-second warmup before switching to Max AC and Max fan speed.
The OEM Setup: 1991 GT Convertible
First up was the 1991 GT with the original HVAC system. Aside from replacing O-rings to fix leaks and recharge the system with R134, everything else is original: compressor, evaporator, condenser - the whole nine yards. This is important, because this cars HVAC system will mirror what 99% of all current day Foxbody owners are running.
After the one-minute warmup, I cranked the system to Max AC and took measurements at the vent. The results:
Wind speed: approximately 12–13 mph
Vent temperature: stabilized around 49–50°F
Not bad at all for a 30-plus-year-old system. It definitely blows cold, and for an untouched OEM setup, it performs respectably.
The Aftermarket Challenger: 1992 Coupe with Vintage Air
Next, I fired up the 1992 Notch equipped with the full Vintage Air Gen 5 Surefit Foxbody kit. This system includes a completely new HVAC box, evaporator, heater core, compressor, condenser, and all new lines. It had just been charged, and aside from confirming cold air at the vents, this was essentially its first real test.
After the same 60-second warmup, I switched to Max AC and Max fan. I did move the gauge between vents to get the most accurate reading, but the difference quickly became obvious.
Wind speed: roughly 14–15 mph
Vent temperature: dropped rapidly to the mid-30s°F
The temperature kept falling even after I stopped recording, hovering around 35°F—and it felt very cold. Noticeably colder than the OEM system, and the airflow felt stronger as well.
The Results (and a Fair Disclaimer)
Now, full disclosure: yes, this is a brand-new aftermarket system versus a mostly original 1991 setup with 96’000 miles on it. That’s a fair point, and I get why some people might call that an uneven comparison.
But here’s the thing—most Foxbody owners are closer to the 1991 example. Maybe you’ve replaced a compressor or an evaporator, but you’re still running the original fan and core design. From that perspective, this test gives a realistic picture of what most people are dealing with versus what’s possible with a modern aftermarket system.
Final Verdict: Trophy Goes to Vintage Air
For all intents and purposes, the Vintage Air system takes the win. It pushed air about 2–3 mph faster than the OEM setup, but the biggest difference was temperature. The aftermarket system got dramatically colder - and faster - than the stock system ever did.
You can feel the difference immediately. If you’ve ever wondered whether a modern HVAC kit is worth it in a Foxbody, this test makes a strong case.
This was a fun experiment, and I’m looking forward to actually enjoying that ice-cold air once the weather warms up.