This article initially appeared in PS 801 (Aug 19), p. 14-15.
Summer temps demand a lot from vehicle air conditioning systems, especially up-armored FMTVs. To get the most out of your FMTV A/C, keep it charged to the right pressure levels.
For FMTV/LMTV A1P2 models, use 3.75 LBS of refrigerant, as indicated in TM 9-2320-333-23&P (Jun 19), also known as IETM EM 0372 (Nov 18).
Although these charge weights represent a baseline, the
actual psi will vary, depending on ambient temperatures. Use these charts as your guide:
Temperature
(°F) |
HFC-134a
PSI |
|
Temperature
(°F) |
HFC-134a
PSI |
| -60 |
21.8 |
|
55 |
51.1 |
| -55 |
20.4 |
60 |
57.3 |
| -50 |
18.7 |
65 |
63.9 |
| -45 |
16.9 |
70 |
70.9 |
| -40 |
14.8 |
75 |
78.4 |
| -35 |
12.5 |
80 |
88.4 |
| -30 |
9.8 |
85 |
94.9 |
| -25 |
6.9 |
90 |
103.9 |
| -20 |
3.7 |
95 |
113.5 |
| -15 |
0.0 |
100 |
123.6 |
| -10 |
1.9 |
105 |
134.3 |
| -5 |
4.1 |
110 |
145.3 |
| 0 |
6.5 |
115 |
157.6 |
| 5 |
9.0 |
120 |
170.3 |
| 10 |
12.0 |
125 |
183.6 |
| 15 |
15.0 |
130 |
197.6 |
| 20 |
18.4 |
135 |
212.4 |
| 25 |
22.1 |
140 |
227.9 |
| 30 |
26.1 |
145 |
244.3 |
| 35 |
30.4 |
150 |
261.4 |
| 40 |
35.0 |
155 |
279.5 |
| 45 |
40.0 |
160 |
298.4 |
| 50 |
45.3 |
165 |
318.3 |
HMMWV A/C Charge Weights
Charge weights for HMMWV air conditioning systems are found in TM 9-2320-280-13&P (Jan 14) also known as IETM EM 0338 and TM 9-2320-387-13&P (Mar 14) also known as IETM EM 0323.
Here’s a chart to keep handy on hot summer days!
| Vehicle |
Charge Weight * |
| M997 ** |
2.6 lbs |
| Up-armored 4-seat HMMWV |
3.5 lbs |
| Up-armored 2-seat HMMWV |
1.4 lbs |
| M997A3 |
9.0 lbs |
| HMMWVs with front-mounted A/C |
2.0 lbs |
NOTES:
* In the original article, charge weights were listed in pounds (lbs) and ounces. Here they're listed in lbs to match what's found in the TM/IETM.
** The original article included M997A1 and M997A2 HMMWVs; they are no longer supported.