Not getting the cooling performance you expected from your reefer or HVAC van? The issue might not be mechanical at all.
A lot of operators think that if the cargo area isn't cooling down right, the reefer unit or HVAC system must be broken, but that's not always true. We've witnessed many situations when everything on the refrigeration side is fine, but the temperature won't decrease like it should.
One of the prevalent and yet ignored issues is that of inadequate insulation.
A Reefer That Looked Fine… But Wasn’t
For example, a van is brought in for diagnostics because it isn't cooling down quickly enough. It looks like the reefer unit, which runs on R134a, is working fine.
The readings show:
- Low-side pressure: At 30 psi.
- High-side pressure: At 130 psi.
- Delta T (ΔT): Around 20°F.
Quick ref—What’s Delta T?
Delta T, also referred to as "ΔT," represents the difference between the temperature of incoming air and outgoing air. In most systems, what we see is an optimal range of 15°F to 25°F. We note that 20°F is in the best range.
So from a technical standpoint, the system was performing as expected. But in the cargo area, we were seeing that temperatures didn't drop as they should have.
Missing Door Insulation = Constant Cold Loss
The problem is that the doors on the back don't have their insulation panels on them. Even though the door covers may seem like a small thing, they are very important for keeping the temperature inside the car comfortable. That way, cold air leaves the fridge faster than it can come back in. Because of the bare metal, heat from the outside comes in when it's hot.
We did a comparison with infrared images before and after we installed the insulation, which showed that:
- Before insulation: The rear ones were blue, which is a sign of heat transfer and cold air loss.
- After insulation: The same doors are red, which means the thermal barrier is holding in, and cold air is staying inside.
That one change made cooling work much better without needing to change any part of the reefer system itself.
What You Should Know About Pull-Down Time
Pull-down time is the amount of time it takes to cool the cargo area to the right temperature.
In typical conditions, you should expect the inside to drop by about 1°F every minute. However, it slows down as it gets closer to freezing. For instance, it might only take 25 minutes to go from 65°F to 40°F, but it might take just as long to go from 40°F to 32°F.
Pull-down time isn’t just about the reefer unit. What really affects it is:
1. Outside Temperature: The reefer must work harder when the temperature is in the 80s, 90s, or higher, especially in direct sun. The greater the heat of the environment, the slower the cooldown; also, proper insulation becomes even more important.
2. Van Color: The color of a van is more significant than we often realize. A black or navy van can run 20 to 40 degrees hotter in the sun than a white one. That heat is transferred inside, which makes for harder and longer cooling.
3. Insulation Quality: A refrigerated unit will not work well if the van is not properly sealed, even at the highest end of the range. Your system can't work if there are problems like missing door covers, holes in the ceiling or wall panels, or the wrong materials being used. Insulating your room is important because it keeps the cold out and the heat in. If you don't, you'll waste energy and put stress on your equipment.
Read More: Best Materials for Cargo Van Wall Liners
What We Offer to Fix It
We put in high-performance insulation systems at Volition Components that are made for reefer vans, HVAC builds, and cargo conversions. We can help you keep the temperature inside your vehicle under control or move things that are sensitive to temperature.
Our commercial-grade liner kits include:
- Full interior wall and ceiling insulation
- Side and rear door liners
- Thermal barriers with sound-deadening options
- Moisture-resistant materials and professional-grade adhesives
We partner with trusted manufacturers like Legend Fleet Solutions and other commercial suppliers, which means that your upfit performs in real-world conditions, not just in theory.
Better Results, Less Strain, No Equipment Swap Needed
When a system is not cooling down fast enough, many seek to replace components. In most cases, however, the solution is much simpler: seal the box, retain the cold, and let your reefer do what it is designed to do.
This is the same for HVAC-equipped vans. At the start, if you aren’t getting the coolness you expect, it is very likely that the insulation is at fault.
Summary
Here is a brief overview of what you should take away from this.
Key Points to Remember:
- Mechanical systems' performance is a result of proper insulation.
- Pull-down time should be about 1°F per minute, which, of course, does vary by weather and interior materials.
- Dark-colored vans absorb more heat than light ones.
- Proper insulation of doors, ceilings, and walls is what you want for cargo temperatures.
- Before blaming your reefer, make sure the thermal barrier isn’t the issue.
Ready to Improve Your Van’s Performance?
Whether you are putting together a new reefer van or going over one that is already out for repair, we can help. From full interior insulation kits to thermal diagnostics and infrared scanning, we have the tools and experience to do the job right.
Reach out to us or drop by the shop for info on our insulation options and upfitting solutions.
And while you’re here, ask to see the thermal camera, where we’ll show you exactly what’s happening behind the walls.